Super Facts

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.

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>, 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>, 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>, 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 19^th 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

#63 : Evolution is a Fact
#73 : The Second Law of Thermodynamics Does Not Contradict Evolution
#81 : Humans and Chimpanzees Have a Common Ancestor
#82 : All Life Have a Common Ancestor
#84 : Birds are Avian Dinosaurs
#85 : The Evolution of Whales is No Longer a Mystery
#86 : Early Homo Sapiens lived at the same time as many other human species
#89 : There is Strong Evidence for Macroevolution
#104 : The Evolution of Eyes is Convergent
#114 : Neanderthals and Humans Interbred

To see the Other Super Facts click here

Smorgasbord Blog Magazine Sharing Accents are very difficult to lose

Smorgasbord Blog Magazine – Thomas Wikman’s Superfacts – #Accents are very difficult to lose

Please visit this Smorgasbord Blog Magazine post, which is sharing my post Accents are very difficult to lose, as well as showcasing my Leonberger dog book.

Swedish flag on blue sky with white clouds. 6 June. Flag. Celebration Holiday National Day Festive. | Accents are very difficult to lose — Flag of Sweden in sunny rays high on the flagpole. Shutterstock asset id: 2344367957 by GenOMart.

An American flag on the background of a blue sky. — The flag of the United States of America Shutterstock asset id: 2566207745 by Ashley Grise.

French flag against blue sky — Flag of France. Shutterstock asset id: 2457252007 by Kyrylash Stanislav.

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.

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/>, 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>, 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

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Shapes with Limited Volume and Infinite Area

Super fact 113 : There are shapes that have a limited volume but an infinite surface area. Two examples are Gabriel’s Horn and the Menger Sponge.

A trumpet looking shape with a decreasing thickness as you move right along the trumpet. It stretches out infinitely far. | Shapes with Limited Volume and Infinite Area — 3D illustration of Gabriel’s horn. RokerHRO, Public domain, via Wikimedia Commons.

You get Gabriel’s horn by rotating the curve y = 1/x around the x-axis in a coordinate system with the horn starting at x = 1, and y = 1, as in the picture below. Well, you can choose other start values too. A Gabriel’s horn with a beginning radius 1, or widest radius 1, (as in this example) will have a volume equal to pi. Pi is a popular constant. However, it will have an infinite surface area.

This seems like a paradox. The amount of paint you need to fill up Gabriel’s Horn (with widest radius = 1) is pi. However, the surface area of the outside and inside is infinite. So, wouldn’t you need an infinite amount of paint to paint the inside of Gabriel’s Horn? The amount of paint you need to fill up the horn should be more than if you just paint the inside, shouldn’t it? What’s going on? The solution to the paradox is to realize that the radius of Gabriel’s Horn will become increasingly small as it stretches out to the right, and for a coat of paint to take up volume it must have thickness. This is explained well here.

A coordinate system with the curve y = 1/x beginning at x = 1 and y =1. — If you rotate this curve around the x-axis, you get a trumpet shape. That is Gabriel’s Horn. I was lazy and drew this using ChatGPT instead of drawing it myself.

To understand why it is possible for the surface area of Gabriel’s Horn to become infinite you can imagine two cylinders of equal volume, one short (and thick), and one long (and thin). The longer and thinner cylinder will have a larger surface area as shown in the picture below. As Gabriel’s Horn is stretched out and getting thinner and thinner you get an infinite surface area, as you go towards infinity, while the volume does not become infinite. This is analogous to the infinite series in my previous post where adding an infinite number of subsequently smaller addends results in a finite number (corresponding to the volume being finite in this case).

The Menger Sponge

The picture shows a Menger Cube with square holes in its surface. There are also square holes inside the cube. | Shapes with Limited Volume and Infinite Area — An illustration of M4, the sponge after four iterations of the construction process. Niabot, CC BY 3.0 https://creativecommons.org/licenses/by/3.0, via Wikimedia Commons

The way you construct a Menger sponge or a Menger cube is by starting with a cube.
Then divide every face of the cube into nine squares in a similar manner to a Rubik’s Cube, dividing the cube into 27 smaller cubes.
Then remove the smaller cube in the middle of each face and remove the smaller cube in the center of the larger cube, leaving 20 smaller cubes. This is a level 1 Menger sponge.
Repeat steps two and three for each of the remaining smaller cubes and continue to iterate infinitely many times.

As you are repeating this process over and over the volume of the Menger sponge will decrease a little bit in every step whilst the area will grow towards infinity.

Four cubes, each representing a step in the creation, M0, M1, M2, M3 — An illustration of the iterative construction of a Menger sponge up to M₃, the third iteration.

The Jerusalem Cube is like the Menger sponge/cube but instead of removing cubes you remove cross or plus looking 3D shapes from the larger cubes.

Looks like Menger cube but with different shapes. | Shapes with Limited Volume and Infinite Area — Third iteration Jerusalem cube. Affixidien, CC BY-SA 3.0 https://creativecommons.org/licenses/by-sa/3.0, via Wikimedia Commons

There are many other shapes with a finite volume and infinite surface area. However, there are no geometric shapes with an infinite volume and limited surface area.

Other Mathematics Superfacts

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Infinite Series Magic

Super fact 112 : Adding infinitely many numbers may result in a finite number. In addition, adding infinitely many numbers may result in an irrational important constant such as Pi. The same holds true for infinitely nested radicals (square roots).

The picture features an infinite series and a rectangle divided into differently colored smaller and smaller rectangles. | Infinite Series Magic — The differently colored rectangles represent the fractions in the equation. Each subsequent addend is the half of the previous. Despite having an infinite number of addends, the total sum is just 1.

That you can add infinitely many numbers and get a finite number as the result is possible to understand if you imagine cutting a rectangle into smaller and smaller pieces and then adding them to get the rectangle back. If you start with half the rectangle and then you add the half of the remaining half and then the half of that remaining half, etc., you can keep doing that forever without exceeding the size of the rectangle. This is illustrated in the picture above. Note all these pictures are drawn by me.

If you’ve never seen an infinite series before this may come as a surprise. However, what is even more surprising is that you can add an infinite number of addends that are constructed from simple patterns and get all kinds of surprising results including irrational numbers with special meaning such as pi. You can easily find thousands of examples in mathematical handbooks and online. This reality is important in mathematics and our understanding of the world, as well as surprising, and therefore a super fact in my opinion.

Three infinite series following very simple patterns. Two results in a simple fraction and the third yields the constant pi. — Three fascinating examples of infinite series. Note that I indicate multiplication using a star *.

Infinitely Nested Radicals

In addition, to adding an infinite number of addends you multiply an infinite number of factors and end up with a non-infinite (finite) result. You can even have an infinite number of nested radicals. To explain what a radical is. A square is a number multiplied by itself. For example, the square of 5 is five times five, which is twenty five. A cube is a number multiplied by itself three times. The cube of five is five times five times five, which is one hundred and twenty five. The square is denoted by adding a superscript of 2 (5 with a superscript 2). The cube is denoted by adding a superscript of 3 (5 with a superscript 3).

The square root is the opposite of the square. The square root of twenty five is five. The cube root is the opposite of the cube. The cube root of one hundred and twenty five is five. The square root and the cube root are examples of radicals. Radicals are indicated by using a little house on top of the number as shown in the pictures below. For radicals that are not square roots you add a number indicating what type of radical you have. The cube root has the number three above the house. All the examples below are square roots and in those cases the number two is left out.

The three pictures below show one example of infinitely nested radicals (square root) using numbers n(n-1) repeatedly in the square roots. When n = 2 then n(n-1) is 2*1 = 2. When n = 3 then n(n-1) is 3*2 = 6, etc.

The picture displays the generic formula for this infinitely nested square root and three examples. | Infinite Series Magic — Infinitely nested square roots using n = 2 is the same as 2. Infinitely nested square roots using n = 3 is the same as 3, etc.

Infinitely nested square root for n = 5,6,7,8

Infinite Series Magic — Infinitely nested square root for n = 9,10,11,12

Infinite Series and Pi

The constant pi is a special mathematical number that tells you exactly how the distance around the edge of any circle compares to the distance straight across the middle (diameter). Pi is an irrational number, meaning it cannot be expressed as a fraction and when written as a decimal it has an infinite number of decimals that have no repeating patterns. Despite pi being irrational, it shows up as the result of a very large number of infinite series that follow surprisingly simple patterns.