Tag: Evolution

Transitional Fossils are not rare

Superfact 115: Transitional Fossils are not rare. Fossilization itself is a rare event and despite that paleontologists have discovered numerous transitional fossils that illustrate the gradual evolution of, for example, humans, whales, horses, rhinos, other mammals, birds, fish to amphibians (fishapods), etc.

Skulls of different types of hominids, displayed in a museum. | Transitional Fossils are not rare
Shutterstock asset id: 2500328883 by Rebel Red Runner

As mentioned, fossilization is an extremely rare event and therefore the fossil record is expected to be incomplete and to contain “gaps”. Additionally, many transitional species had smaller populations or lived in environments where preservation was difficult. Another thing to keep in mind is that evolution is not a linear chain. There are no perfect halfway points. Species evolve and diversify in a branching tree. A transitional fossil is any fossilized remain of a life form that exhibits traits common to both an ancestral group and its later descendant group, meaning every organism is technically transitional.

Blue color on the left slowly fading into the red color on the right.
Microevolution is small changes resulting in large changes over time. Macroevolution are multiple microevolutionary steps turning into “macroevolution”.

What people tend to focus on is transitional fossils between ancestral groups and descendant groups that are far part, and feature interesting differences, and are far back in time, such as the land living ancestors of whales and modern whales, which before such transitional fossils were found represented a large “gap”. What may come as a surprise to many people is that many so called “gaps” have been filled out by new fossil discoveries. You can of course always add new “gaps” as old ones are filled in. You can always imagine as many gaps as you’d like.

However, gaps, or “missing links”, or the quantity of transitional fossils, etc., does not represent a problem for the theory of evolution as often claimed. In other words, Transitional Fossils are not rare.

The photo shows a Australopithecus afarensis skeleton on a wooden background.
Australopithecus afarensis – walking posture. Chiswick Chap, CC BY-SA 3.0 https://creativecommons.org/licenses/by-sa/3.0, via Wikimedia Commons

The picture above shows the famous Lucy skeleton. She belonged to a species called Australopithecus afarensis, which is a famous transitional species in human evolution, bridging the gap between more primitive, quadrupedal ancestors and the later Homo genus.

Below is a simplified cladogram showing hominin ancestry including Australopithecus afarensis. Notice that we did not descend from chimpanzees, but we have a common ancestor with chimpanzees. This was discovered from DNA analysis.

At the bottom of the cladogram is a box that says “hominin ancestor. A tree branches off from this box. On the left is a chimpanzee and the right a tree for seven hominin species including modern humans.” | Transitional Fossils are not rare
Simple cladogram showing evolution of modern man from Hominid Ancestor Shutterstock Asset id: 2093535535 by CLOUD-WALKER.

The creationist talking point about “missing links”, or the supposed lack of transitional fossils is misguided (see point 13) but very common in popular culture. Not too long ago I read a book “Darwin on trial” by Phillip E. Johnson, which is often considered to be a scientific and powerful creationist rebuttal of the theory of evolution. This book featured many erroneous assertions including this talking point and, in addition, it misrepresented the fossil record with respect to transitional fossils.

Pretty much all of the around 300 Amazon reviewers for this book bought his arguments and gave the book five stars. Only a few well informed individuals saw the problems. I have also come across this argument many times in my personal life and on social media, and I know a lot of people around the world accept it. Millions, if not hundreds of millions of people believe something that is false on this important topic. That is why I consider “Transitional Fossils are not rare” a super fact.

Some Famous Transitional Fossils

Technically all fossils can be considered transitional fossils and there are hundreds that have been recognized to have clear and interesting transitional features. Below I am mentioning just a few of those. I’ve already mentioned, “Lucy”, the hominid Australopithecus afarensis which represents an evolutionary transition between modern bipedal humans and their quadrupedal ape ancestors. We have found a few hundred Homo erectus fossils, and naturally Homo Erectus is considered another transitional fossil(s) that is crucial to human evolution. It bridges the gap between more primitive, ape-like hominins (like Australopithecus) and modern humans (Homo sapiens).

An almost intact Homo Erectus skull.
H. e. georgicus (above) is an early subspecies of Homo Erectus. It represents one of the earliest dispersals out of Africa about 1.8 million years ago. Gerbil, CC BY-SA 4.0 https://creativecommons.org/licenses/by-sa/4.0, via Wikimedia Commons.

As a side note, according to this article, Homo Erectus genetic material was recently sequenced for the first time, and it shows ‘deep genetic links’ with modern humans. Since DNA material degrade by time and Homo Erectus lived hundreds of thousands of years ago, that is quite remarkable.

Another famous transitional fossil is Tiktaalik roseae. Tiktaalik roseae is a link in evolution from swimming fish to four-legged vertebrates. Tiktaalik lived 375 million years ago, and its skeletal structure shows that it could prop itself up in shallow water and use its limbs for support as most four-legged animals do, and its head resembled that of a crocodile. It also had other characteristics that were like both fish and four legged animals.

The illustration shows a fish like animal with a body resembling something in between a fish and a reptile.
Life restoration of Tiktaalik roseae. Nobu Tamura (http://spinops.blogspot.com), CC BY-SA 3.0 http://creativecommons.org/licenses/by-sa/3.0/, via Wikimedia Commons.
This illustration shows the crocodile like head more clearly and the Tiktaalik roseae is halfway up from the water. | Transitional Fossils are not rare
Another illustration of Tiktaalik roseae. Zina Deretsky, National  Science Foundation, Public domain, via Wikimedia Commons.

Archaeopteryx is a birdlike dinosaur that retained reptilian features such as teeth and a bony tail while having advanced flight feathers. 14 Archaeopteryx fossils have been found. Partially because of transitional fossils found Birds are now reclassified as Avian Dinosaurs.

Original Archaeopteryx skeleton embedded in rock.
Archaeopteryx lithographica, specimen displayed at the Museum für Naturkunde in Berlin. (This image shows the original fossil – not a cast.) H. Raab (User: Vesta), CC BY-SA 3.0 <https://creativecommons.org/licenses/by-sa/3.0&gt;, via Wikimedia Commons.
Closeup of fossilized scary petrified Archaeopteryx transitional fossil between dinosaur and modern birds remains in stone with details of the skeleton with skull and bones. | Transitional Fossils are not rare
Another Archaeopteryx fossil. Shutterstock Asset id: 1913076019 by Natalia van D.

Caudipteryx was a small oviraptorosaurian dinosaur that lived 125 million years ago. It had teeth but was otherwise very birdlike. It was likely a swift runner. You can read about another dozen interesting dinosaur to bird transitional species in my post “Birds are Avian Dinosaurs”.

A bird like skeleton
Caudipteryx zoui, Skelett – Untere Kreide – Liaoning/China – aufgenommen im Museum am Löwentor, Stuttgart. Ra’ike (see also: de:Benutzer:Ra’ike), CC BY-SA 3.0 <https://creativecommons.org/licenses/by-sa/3.0&gt;, via Wikimedia Commons.

Thrinaxodon is a 230-million-year-old cynodont, in other words, a mammal-like reptile. Its posture was something between a reptile and a mammal, it had mammal like teeth, it was likely warm blooded, and mammal like ear drums. However, it laid eggs, its spine and jaw were like that of a reptile, and it had a light sensor on its forehead typical for reptiles.

A hairless animal that looks like a cuddly mammal.
Nobu Tamura (http://spinops.blogspot.com), CC BY-SA 3.0 http://creativecommons.org/licenses/by-sa/3.0/, via Wikimedia Commons.

Eohippus was Also known as Hyracotherium, this 50-million-year-old ancestor of the horse was dog-sized and had four toes on its front feet and three on its back.

Three small horse like animals. | Transitional Fossils are not rare
Eohippus illustration. Charles Robert Knight, Public domain, via Wikimedia Commons.

Cooksonia lived 425 million years ago and is considered the oldest known vascular plant (have specialized tissue to transport water).  It is therefore a crucial evolutionary transition between primitive, non-vascular bryophytes (like mosses and liverworts) and the first true vascular plants (like ferns and advanced tracheophytes).

Mushroom looking plant that is partially green.
A cartoon of Cooksonia, reconstructed with non-photosynthetic axes, dependent on its gametophyte. Smith609Ground texture from  Image:Mud closeup.jpg, CC BY 3.0 <https://creativecommons.org/licenses/by/3.0&gt;, via Wikimedia Commons.

The case of the whales did present a bit of a mystery for a while. Scientists recognized that whales descended from land animals already in the 19th century. However, it was not until the 1980’s that intermediate fossils for whale evolution were found.

In addition, molecular and genetic / DNA studies showed that Hippopotamus and whales were closely related. Until then the evolution of whales was a bit of a mystery and creationists frequently mocked the lack of intermediate fossils for whale evolution. However, as you can see in my super fact post “The Evolution of Whales is No Longer a Mystery” we’ve found dozens of intermediate (transitional) fossils between land mammals such as Pakicetus and modern whales. Below is an Ambulocetus skeleton. To see the other transitional species (with illustrations) check my link.

A skeleton of an Ambulocetus hanging on a wall.
Fossil of Ambulocetus, an extinct whale- Took the photo at Naturalis museum, Leiden. Ghedoghedo, CC BY-SA 3.0 https://creativecommons.org/licenses/by-sa/3.0, via Wikimedia Commons.

I said that there were hundreds of transitional fossils that have been recognized to have clear and interesting transitional features. Well, that might be many thousands. In any case, transitional fossils are not lacking and are not rare. The mystery of the missing links is a myth.

Other Super Facts Related to Evolution

To see the Other Super Facts click here

Neanderthals and Humans Interbred

Superfact 114: Early humans (early Homo sapiens) lived at the same time as many other homo species including Neanderthals (Homo Neanderthalensis) and Humans and Neanderthals Interbred.

Two skulls facing each other. Art Study - Old Textured Paper Vintage Antique Poster style (Vintage Version). | Neanderthals and Humans Interbred
Neanderthals Archaic Extinct Human Skull Vs Modern Human Skull Comparison. Shutterstock Asset id: 2238778267 by Winters860

It’s been known for more than a decade that ancient members of our species, Homo sapiens, met and mated with our evolutionary cousins, Neanderthals. If you have read the Savage Land trilogy by Jacqui Murray, or you have taken a DNA test from, for example, 23AndMe, then you already knew that. Today, up to 2% of the genomes of people outside sub-Saharan Africa originated from Neanderthals. The Neanderthal genome was successfully sequenced in 2010. You can read more about it here. More recently, an analysis of Neanderthal X chromosomes found that most cross-species couplings involved Neanderthal males and modern human females.

Photo of a reconstruction of a Neanderthal man
Reconstruction of a Neanderthal by Natural History Museum. Werner Ustorf, CC BY-SA 2.0 https://creativecommons.org/licenses/by-sa/2.0, via Wikimedia Commons

My wife and I took a DNA test with 23AndMe to find out about inherited diseases as well as our ancestry. I found out that my ancestry was 99.8% Northwestern European, 85.3% Scandinavian/Sweden/Norway, 14.4% Finnish, 0.1% other Northwestern European, and 0.2% Siberian. I also found out that I had strong Neanderthal ancestry. The report said that I have more Neanderthal variants than 99% of customers. Even though this kind of information is fun, it is risky to have some of this information exposed, so I deleted it.

Man geneticist. Doctor sits at table in genetic laboratory. Chains of DNA or RNA. Sequencing human genome. Doctor studies DNA. Geneticist conducts scientific experiments Geneticist looks at test tubes
Geneticist sequencing human genome Asset id: 2479929725 by FOTOGRIN

Anyway, I consider this a super fact because it comes as a surprise to many that humans and Neanderthals interbred, and that many of us therefore have traces of neanderthal DNA. It is also an important fact that we know is true.

This map of Europe and West Asia shows the region where Neanderthals have been found. | Neanderthals and Humans Interbred
Known Neanderthal range in Europe (blue), Southwest Asia (orange), Uzbekistan (green), and the Altai mountains (violet), as inferred by their skeletal remains (not stone tools). There were 165 such places by 2017. Nilenbert, N. Perrault, auteur du guide complet du canotageI, CC BY-SA 3.0 <http://creativecommons.org/licenses/by-sa/3.0/&gt;, via Wikimedia Commons

Early Homo Sapiens lived at the same time as many other human species

Early humans, early homo sapiens, lived at the same time as many other human species, not just Neanderthals. Early Homo sapiens lived at the same time as Denisovans, Homo floresiensis, Homo naledi, Homo luzonensis. Homo heidelbergensis, Homo erectus, and maybe other species as well.  Neanderthals interbred with homo sapiens and died out around 40,000 years ago. The Denisovans also interbred with homo sapiens and died out around 30,000 to 50,000 years ago. Moreover, Homo Neanderthalensis interbred with Homo Denisova. You can read more here and here.

The map shows the movement of Homo heidelbergensis originating in Africa and moving into Europe and Asia with Neanderthals (in yellow) emerging in Europe and moving into Asia. The Denisovans emerged in Asia and spread further east.
The evolution and geographic spread of Denisovans as compared with Neanderthals, Homo heidelbergensis and Homo erectus. John D. Croft at English Wikipedia, CC BY-SA 3.0 https://creativecommons.org/licenses/by-sa/3.0, via Wikimedia Commons.

Speciation is considered relative

Homo Neanderthalensis and Homo Sapiens were different species, so it may seem strange that they could interbreed. However, species is a complex non-static concept, and it is considered relative.

It is often said that two animals belong to the same species if they can interbreed in nature and produce viable, fertile offspring. However, it is not that simple. An animal A may be able to successfully interbreed with an animal B, and that animal B may be able to successfully interbreed with an animal C, but animal A and C cannot interbreed. Animal A could be said to be a different species relative to animal C, but animal B could be said to be the same species as both animal A & C using the definition above. A great geography related example of this is ring species. In a ring species, gene flow occurs between neighboring populations of a species, but at the ends of the ring the populations don’t interbreed.

The picture depicts different subspecies as little colored circles centered around a big lake. The color changes a little bit at the time. All the circles next to each other can interbreed. | Neanderthals and Humans Interbred
Illustration of ring species, an example of how speciation can be relative. All the circles next to each other can interbreed but at the end it no longer works. Andrew Z. Colvin, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0&gt;, via Wikimedia Commons

For the case of Neanderthals and Homo sapiens (and Denisovans); at certain points in history, you could consider Homo Neanderthalensis and Homo Sapiens to be different subspecies rather than different species. That is why you sometimes hear the terms Homo Sapiens Neanderthalensis and Homo Sapiens Sapiens. I can add that Homo sapiens certainly got around, as you can see on the map below.

A world map showing portions of Africa being yellow and red, and portions of Asia being yellow and dark yellow with red arrows representing migrating Homo Sapiens. The map features several time markers representing the arrival of Homo Sapiens. | Neanderthals and Humans Interbred
The spread of Homo Erectus (yellow), Homo Sapiens (red) and Homo Neanderthalensis (dark yellow). NordNordWest, Public domain, via Wikimedia Commons

Super fact posts related to this one

To see the Other Super Facts click here

The Evolution of Eyes is Convergent

Superfact 104: The evolution of eyes is convergent, meaning different, unrelated animal species independently evolved similar types of eyes. Biologists estimate that eyes have evolved independently between 40 to over 65 different times across various lineages. An example is the evolution of Cephalopod eyes (like squid and octopus) and vertebra eyes.

Esther’s writing prompt: May 20, 2026: Eyes

Click here to join in.

First of all, eyes evolved. Creationists often say that eyes are too complex too have evolved. That is because the eye is composed of many interdependent, finely tuned parts, for example, the cornea, iris, retina and lens. And that it cannot function without all those components already evolved. This is referred to as the argument for irreducible complexity.

The problem with that argument is that evolution is not linear. The various intermediate steps may not have functioned as the final product but could still have provided evolutionary advantage. There are many intermediate “eyes” existing today in nature. As you can see in the picture below the evolution of the vertebra eye did not start with all the current parts.

The picture shows six stages of the evolution of the vertebra eye. First a region of photosensitive cells and nerve fibers. Second a depressed/folded area that allows limited directional sensitivity. Thirdly, a “Pinhole” eye that allows finer directional sensitivity and limited imaging. Fourth, a transparent humor develops in an enclosed chamber. Fifth, a distinct lens develops. Sixth, Iris and separate cornea develop. | The Evolution of Eyes is Convergent
Major stages in the evolution of the eye in vertebrates. Matticus78 at the English-language Wikipedia, CC BY-SA 3.0 http://creativecommons.org/licenses/by-sa/3.0/, via Wikimedia Commons.

In addition, the evolution of eyes is largely convergent. Biologists estimate that eyes have evolved independently between 40 to over 65 different times across various lineages. The cephalopods (like octopuses and squid) and vertebrates (like humans, mammals, birds and fish) evolved their camera-style eyes completely independently. This is one of nature’s most famous examples of convergent evolution, where two unrelated species arrive at the exact same biological solution to survive in their environments.

The fact that eyes evolved and that the irreducible complexity argument does not work comes as a surprise to creationists. That the various kinds of eyes in nature evolved separately but converged on similar complex structures is in general an amazing fact. It is a kind of an important fact that is true. Therefore, it is a super-fact in my opinion.

Eyes Are not an Example of Irreducible Complexity

The evidence that the complexity of eyes is not an example of irreducible complexity is strong. We can trace lineages via DNA and sub-optimality. We can also simulate the evolution of the eye using computers. In a simulation based on mutations and natural selection it took 363,992 generations to evolve an eye from an eyespot (light-sensing organelle) to a complex camera type eye, which probably corresponds to around half a million years. See The Evidence for Evolution by Alan R. Rogers.

I can add a personal anecdote. In my job as a software engineer trying to find better algorithms for sorting mail using the photos of the mail, including the address block, I tried using genetic algorithms. Genetic algorithms is a type of Artificial Intelligence that simulates evolution to create better systems (better algorithms and software). The genes corresponding to the best algorithms were allowed to propagate, recombine and mutate. That was the natural selection component.

What I saw was that the genetic algorithm could evolve the system into a complex and effective system of interdependent complex components that did not exist at the beginning. Several complex components working together did not require that components/parts evolve one after another. They can go through several formats from primitive to advanced and they can have different functions along the way. Some parts might evolve and then disappear and new kinds of parts pop up, as the total algorithm kept evolving. There is no reason to believe that irreducible complexity even exists.

The Vertebra Eye versus the Cephalopod Eye

The cephalopod eye on the right is very similar to the vertebra eye on the left, except it does not have a blind spot.
1 is the retina and 2 the nerve fibers. 3 is the optic nerve. 4 is the vertebrate blind spot. Caerbannog, CC BY-SA 3.0 <http://creativecommons.org/licenses/by-sa/3.0/&gt;, via Wikimedia Commons.

While both eyes share features like a cornea, iris, lens, and retina, they were built from different starting materials and possess some structural differences. In vertebrate eyes, the nerve fibers route before the retina, blocking some light and creating a blind spot where the fibers pass through the retina. In cephalopod eyes, the nerve fibers route behind the retina, and do not block light or disrupt the retina. In other words, the cephalopod eyes not having a blind spot are more perfect than our eyes.

Close up of squid with its eye at the center. | The Evolution of Eyes is Convergent
Look into the loving eyes of the squid. He does not have a blind spot. Atlantic Ocean squid macro photo. Shutterstock asset id: 1859007028 by Rui Palma

My Other Responses to Esther’s Prompts

To see the Other Super Facts click here

There is Strong Evidence for Macroevolution

Superfact 89: There is overwhelming scientific evidence supporting so called macroevolution. Evidence for macroevolution includes the fossil record, molecular biology and DNA, biogeography, comparative anatomy, embryology, suboptimality, vestigial structures, etc.

It is difficult to deny that so called microevolution is happening since it can be directly observed. However, it is quite common to come across claims that there is no evidence for macroevolution or that macroevolution is impossible and unscientific. These claims do not come from mainstream scientists but from creationists. There is no magical barrier between microevolution and macroevolution. Rather, macroevolution is just an accumulation of microevolutionary steps, and it is a fact that those changes have been slowly accumulating over millions and billions of years.

Blue color on the left slowly fading into the red color on the right. | There is Strong Evidence for Macroevolution
Microevolution is small changes resulting in large changes over time. There is no magical wall stopping multiple microevolution changes from turning into macroevolution.

It is often said that macroevolution is when a species evolves into another and that this represents a special barrier, impossible to breach. The existence of fuzzy boundaries between species and the existence of ring species demonstrate that this idea is faulty. See the next section for more information on this. Next after that, I am listing 10 selected types of evidence for macro evolution. If you wish to see an overview of 29+ Evidences for Macroevolution, click here. I can add that scientists do not like to use the terms microevolution and macroevolution since they are nebulous. These terms are more of a creationist thing. That’s why I been prefixing microevolution and macroevolution with “so called”.

Roughly a third of Americans believe the creationist claim that macroevolution is not possible, or that there is no evidence for it, even though we know that there is Strong evidence for macroevolution. Therefore, I consider this a super fact. Note, 97% of scientists support the theory of evolution. This is a brief Wikipedia article on evolution.

Note, this post is long, but if you are interested in it, you could just read a few instead of the evidences instead of all ten.

Speciation is considered relative

It is often said that two animals belong to the same species if they can interbreed in nature and produce viable, fertile offspring. However, it is not that simple.

An animal A may be able to successfully interbreed with an animal B, and that animal B may be able to successfully interbreed with an animal C, but animal A and C cannot interbreed. Animal A could be said to be a different species relative to animal C, but animal B could be said to be the same species as both animal A & C using the definition above. A great geography related example of this is ring species. In a ring species, gene flow occurs between neighboring populations of a species, but at the ends of the ring the populations don’t interbreed.

The picture depicts different subspecies as little colored circles centered around a big lake. The color changes a little bit at the time. All the circles next to each other can interbreed. | There is Strong Evidence for Macroevolution
Illustration of ring species, an example of how speciation can be relative. All the circles next to each other can interbreed but at the end it no longer works. Andrew Z. Colvin, CC BY-SA 4.0 https://creativecommons.org/licenses/by-sa/4.0, via Wikimedia Commons.

Next up are ten selected types of evidence for Macroevolution in no particular order.

The Fossil Record Show an Evolution from Simple to Complex Species

The fossil record is quite extensive and represents 250,000 different species, but it is very far from complete. That is expected. Fossilization is an extremely rare event, and fossils are hard to find. Among the 250,000 fossils from different species there are no Precambrian rabbits or Mesozoic human fossils. If there were, that would have falsified evolution and been evidence for a creator. This example shows first of all that the theory of evolution is falsifiable (all scientific theories have to be falsifiable) contrary to some creationist claims and it constitutes a form of evidence for evolution.

If evolution is true then a scan through the entire sequence of rock strata should show early life to be quite simple, with more complex species appearing only after some time. In addition, the youngest fossils should be those that are most similar to living species. The fact that this is the case is strong evidence for evolution, specifically macroevolution. You can read more about this in this relatively short book, The Evidence for Evolution, by Alan R. Rogers.

A photo of a trilobite fossil.
The fossil record is a lot more solid and much less problematic than the creationist books I have read claimed. Shutter Stock Photo ID: 1323000239 by Alizada Studios

We can Follow Lineages in the Fossil Record

In the fossil record we can also follow lineages; species of animals and plants changing into something different over time. The fossil records show fish changing into amphibians, reptiles changing into mammals, dinosaurs into birds, artiodactyl like mammals into whales, apes into humans, etc. Creationists used to mock the fact that there were no transitional fossils between land mammals and whales and then they found Pakicetus in 1983 and then a lot more. As time passes the more transitional fossils we find.

The Archaeopteryx is embedded in stone with details of the skeleton with skull and bones.
Closeup of fossilized scary petrified Archaeopteryx transitional fossil between dinosaur and modern birds remains. Shutterstock Asset id: 1913076019 by Natalia van D.

The fact that we can follow lineages and that they are consistent with the various dating methods is powerful evidence for evolution. Dating methods include radiometric dating methods (uranium-lead, potassium-argon, carbon-14), and sequencing and superposition, and conditions encoded in fossils such as the length of the day (varied throughout natural history) and more. To read more about dating methods and how we know Earth is billions of years old click here. The picture below illustrates the skull changes of hominids by time.

15 skulls for different hominid species are shown as well as the relations between the species. | There is Strong Evidence for Macroevolution
Homo skull changes of hominids from Wikipedia<>. SimplisticReps, CC BY-SA 4.0 https://creativecommons.org/licenses/by-sa/4.0, via Wikimedia Commons.

Molecular Biology and DNA

Molecular biology and DNA may be our best evidence for macroevolution. Our understanding of DNA has greatly increased over the last couple of decades. The human genome has been sequenced along with that of many other species, and we are able to compare the DNA and the genes of various species, and trace origins.

Man geneticist. Doctor sits at table in genetic laboratory. Chains of DNA or RNA. Sequencing human genome. Doctor studies DNA. Geneticist conducts scientific experiments Geneticist looks at test tubes. | There is Strong Evidence for Macroevolution
Geneticist sequencing human genome Asset id: 2479929725 by FOTOGRIN

Of special interest are pseudo genes, the millions of transposable elements (transposons and retroelements) as well as useless sequences, introns. These segments are especially interesting because they are unaffected by natural selection and therefore mutations pile up in them at a fairly constant rate. By comparing two such segments in two species we can tell how far the species are apart and even how far back in time their common ancestor lived.

Based on the similarity in transposons we know that the closest related living animals to whales and dolphins (outside their order) are Hippopotamus, which confirms what we know from the fossil record of whales and the mammals that whales evolved from. Whales and Hippopotamus have a common ancestor and since we’ve found dozens of intermediate fossils between land mammals and whales, the evolution of whales is no longer a mystery.

This graph shows pictures of a sperm whale, gray whale and hippopotamus on the right, and two whale ancestors at the top and they are connected via lines ultimately showing the common connection point on the far left.
All living cetaceans including whales, dolphins, porpoises, sperm whales and hippopotamids / hippopotamus belong to a suborder of artiodactyls called whippomorpha. Hippopotamus and whales have a common ancestor. Note: I created this image by inserting a few pictures from Wikipedia commons including a mother sperm whale and her calf off the coast of Mauritius, a gray whale in captivity, a hippopotamus and two pre-historic whales (from the section Evolution of Whales – Intermediate Fossils).

Based on the similarity in transposons, pseudo genes, and genes in general (all of the genome) we know that the closest related living animals to humans are chimpanzees and bonobos. In fact, chimpanzees and humans are more closely related than chimpanzees and the other great apes. Based on the genetic record chimpanzees are no longer classified as great apes but as Hominini together with humans. Also based on the genetic record we know that chimpanzees and humans had a common ancestor that lived about six million years ago. The fossil for this common ancestor has not been found, but the information in the DNA can often tell us more than the fossil record.

The pictures show the set of the human 46 chromosomes on the left and the set of the chimpanzee 48 chromosomes on the right. The chromosomes look very similar between the two species, except human chromosome 2 which is split into chromosome 2A and 2B in the chimpanzee.
Comparison between human and chimpanzee karyotypes isolated on background. Shutterstock Asset id: 2432966649 by kanyanat wongsa.
The picture is a graph that shows that gorillas, chimpanzees and humans share a common ancestor with orangutans. In turn bonobos, chimpanzees and humans share a common ancestor with gorillas and finally chimpanzees and bonobos share a common ancestor with humans. | There is Strong Evidence for Macroevolution
Evolution of humans via phylogenetics and differentiation between humans, chimpanzees, and other primates. Shutterstock Asset id: 2448150743 by kanyanat wongsa.
At the bottom of the cladogram is a box that says “hominin ancestor. A tree branches off from this box. On the left is a chimpanzee and the right a tree for seven hominin species including modern humans.”
Simple cladogram showing evolution of modern man from Hominid Ancestor Shutterstock Asset id: 2093535535 by CLOUD-WALKER.

The book Relics of Eden, the powerful evidence of evolution in human DNA by Daniel Fairbanks is good fairly in depth book on this topic.

Biogeography

Biogeographic evidence for evolution / macroevolution is among the oldest types of evidence (Charles Darwin used it) and yet it is very powerful. Biogeographic evidence for evolution shows that species’ geographic distributions result from descent with modification and environmental adaptation, rather than just similar habitats. Key types of biogeographic evidence for macroevolution include species existing only on a certain island, adaptive radiation (e.g., Galápagos finches), tectonic-driven species distribution (e.g., marsupials), and convergent evolution of unrelated species in similar environments.

The picture shows an island with an ancestral finch on the left and multiple other species of finch on the right all feeding on different things.
Adaptive radiation is a rapid evolutionary process where an ancestral species diversifies into a multitude of new species (or subspecies) to fill vacant ecological niches. Shutterstock Asset id: 2707584123 by VectorMine.

One example of biogeographical evidence for macroevolution is with so called oceanic islands. Oceanic islands are not part of a continent but are formed from the sea bottom typically through volcanic activity. Oceanic islands lack native freshwater fish and amphibians, and they rarely harbor native mammals and reptiles. However, freshwater fish, amphibians, mammals and reptiles thrive when introduced to oceanic islands. It’s just that they have to get there in the first place.

Instead, oceanic islands typically feature birds, insects, and plants that can more easily spread long distances. In addition, the species on oceanic islands are typically closely related and appear in relatively few groups. Add the fact that the species on oceanic islands resemble species on nearby continents but they are not the same. This strongly supports the narrative that some species from nearby continents migrated to newly formed oceanic islands and evolved.

The evidence gets even better if you look in more detail. For example, the Hawaiian Islands (oceanic islands) were formed in chronological order from west to east, as the divide between the continental shelves moved. The species on the different islands show a gradual transition in their physical properties and in their DNA as you go from west to east. This supports the narrative that the species hopped from one island to the next as the islands emerged, and then they evolved.

Comparative Anatomy

Similar anatomical structures in different species, such as the similar bone structure in a human arm, a bat wing, and a whale flipper indicate shared ancestry. Another is the heart structures in fish, amphibians, reptiles, birds, and mammals which show a homologous progression of development.

Embryology

Different species share similar developmental stages. For example, early embryos of reptiles, birds, and mammals, including humans, develop pharyngeal pouches that are similar to fish gills. Baleen whale embryos have teeth that are lost by birth, human embryos develop a tail that are later lost, and human fetuses develop hair around week 16-20 that is usually lost but remain on premature babies. The development of embryos goes through stages of similar embryos of fish, then amphibians, reptiles, and then mammals.

Suboptimality

There is a lot of evidence based on so called suboptimality. Our bodies and that of other animals are full of imperfections that make perfect sense from an evolutionary perspective but not much sense if we were created by a creator. One example is the “vas deference”, which follow a circuitous route from the testis up and around the ureter and back down to the penis, instead of going straight to the penis. As the testis gradually moved from inside our bodies (as it was in fish) to the outside, vas deference got stuck around the ureter like a water hose can get stuck around a tree. This makes perfect sense from an evolutionary perspective.

Vestigial Structures

Vestigial structures are non-functional anatomical features, organs, or behaviors that were functional in a species’ ancestors but have lost most or all of their original purpose through evolution. Examples include the whale hind legs, flightless bird wings, the human appendix, the tailbone, wisdom teeth, and goosebumps in humans.

Atavisms

Atavisms are rare reappearances of a lost ancestral trait in an individual. This could happen because ancestral genes are preserved but suppressed but, for example, a mutation allows the gene to be expressed. Examples include a human baby born with a tail, a snake with limbs or a chicken with teeth, dolphins with back flippers, or teeth in chickens. It is rare but evidence for evolution.

Traces of Common Descent

Traces of common descent in species, for example, homologous anatomical structures, similar embryological development, shared genetic codes, and phylogenetic mapping allows the construction of the tree of life. Phylogenetic mapping suggests that organisms inherited fundamental traits from a common ancestor. All life except viruses can be traced back to a common ancestor that lived 4.2 billion years ago. This also constitutes evidence for evolution / macroevolution.

The picture shows how the three domains of life bacteria, archaea, eukaryote, and the relationships between the different phylum in each domain leads back to LUCA (Last Universal Common Ancestor). | There is Strong Evidence for Macroevolution
User: Crion, CC BY 3.0 https://creativecommons.org/licenses/by/3.0, via Wikimedia Commons.

Other Evolution Related Super Fact Posts

I can add that when I was young, I read a lot of creationists books. I was totally sold on creationism but as I started learning about science that changed. One thing all the creationist books that I read had in common was that they avoided discussing the evidence for evolution and they did not provide evidence for creationism. Instead, they focused on trying to discredit evolution. As I learned more about science I came to realize that not even one of those objections were valid. An example is super fact #73 below.

To see the Other Super Facts click here

All Life Have a Common Ancestor

Super fact 82 : All known cellular life descends from a single Last Universal Common Ancestor (LUCA). All animals, all plants, fungi, algae, green and red algae, kelp, phytoplankton, cyanobacteria, amoebas, amoebozoa, diatoms, stramenopiles, rhizaria, hacrobia, all eukaryote, all archaea, all bacteria, all the millions of species on Earth come from one single ancestor known as the Last Universal Common Ancestor – LUCA. Viruses are an exception, but viruses are not considered life.

This AI generated image shows a cell in an ocean and in the background, there are hundreds of other cells or possible life structures. | All Life Have a Common Ancestor
Last Universal Common Ancestor creation Shutterstock Asset id: 2666598705 by Shutterstock AI

LUCA, the Last Universal Common Ancestor, was not the first life form. It was preceded by earlier, simpler life forms that did not survive. LUCA was a single-celled, bacteria-like microorganism that existed roughly 4.2 billion years ago, or about 400 million years after planet Earth first formed. It was the final common ancestor for all currently living organisms. It thrived near hydrothermal vents as part of a larger microbial community before the three domains of life bacteria, archaea, and Eukarya diverged. This is a super fact because it is true, or at least highly probable, it is surprising and amazing and kind of important.

How Do We Know All Life Has a Common Ancestor ?

The answer is genome mining. By surveying nearly 2000 genomes of modern microbes we not only know that all life has a common ancestor (LUCA), that lived roughly 4.2 billion years ago, but we also know that it thrived near hydrothermal vents as part of a larger microbial community. This is analogous to another of my posts “Humans and Chimpanzees Have a Common Ancestor”. By sequencing human DNA and chimpanzee and bonobo DNA we know that humans and chimpanzees have a common ancestor. No fossils, or other information from the past is needed. DNA is a great tool for determining relationships between species and for finding information about past life, without the need of fossils.

To be more specific, the detailed biochemical similarity of all current life makes the existence of LUCA widely accepted by biochemists. There is a Universal Genetic Code, which means that nearly all living things use the same DNA/RNA-based genetic code to translate genetic information into proteins. There is a shared molecular machinery, for example, all life relies on ribosomes for protein synthesis, similar energy carriers like ATP, and the same 20 amino acids. All life uses the same mirror-image form of molecules, a signature of a single, common ancestry. In addition, there is a “core” set of 355 gene families present in both modern bacteria and archaea, which were likely inherited from LUCA. Finally, we have phylogenetic mapping, protein-sequence-based phylogenetic trees converge on a single root, indicating a common ancestry for all life. See the phylogenetic tree of life below.

The picture shows how the three domains of life bacteria, archaea, eukaryote, and the relationships between the different phylum in each domain leads back to LUCA.
User: Crion, CC BY 3.0 https://creativecommons.org/licenses/by/3.0, via Wikimedia Commons.

Below is another view of the diversification of life that focuses on the inventions made by life.

This tree of life picture shows a root representing a common ancestor and from it sprouts various inventions of life DNA, mitochondria, nuclei, chloroplasts, organs, hair, and much more.
The evolutionary tree of life showing diversification, branching and key characteristics of each branch. Shutterstock Asset id: 228953155 by Zern Liew

It should be noted that in addition to viruses there were likely other forms of life that existed alongside LUCA or before it. There was likely non-cellular life as well as cellular life that died out, RNA-based life, self-replicating nucleic acids, etc. It should also be noted that if some of the large viruses were to be reclassified as life, or a life form not based on LUCA were to be discovered then our “current LUCA” would no longer be LUCA, but just the ancestor of “almost all life”. That would still be amazing, just slightly less so.

The existence of LUCA brings up an interesting question. What would happen if we found DNA based life on another planet and its DNA showed that it also originated from LUCA ?

Other Evolution Related Super Facts

To see the other Super Facts click here