Biological Anthropology Discussion evolution Paleoanthropology

Evolution’s Place in Anthropology

Anthropology is the study of humans.  It's the study of our cultural diversity and developments. Our similarities and differences. It's the study of our history--hopefully without some of the drawbacks of nationalism that History is criticized for. It's the study of our shared heritage. And that includes or place in the Animal Kingdom. So in order to understand the biological aspects of the field of anthropology, we need to have a basic understanding of evolution.

Anthropology is the study of humans.  It’s the study of our cultural diversity and developments. Our similarities and differences. It’s the study of our history–hopefully without some of the drawbacks of nationalism that History is criticized for.

It’s the study of our shared heritage. And that includes or place in the Animal Kingdom.

So in order to understand the biological aspects of the field of anthropology, we need to have a basic understanding of evolution.

Evolution is change in the heritable characteristics of biological populations over successive generations. Meaning that over time, populations will slowly drift from a given starting point.

It’s synonymous with Charles Darwin, who famously published On the Origin of Species in 1859. In this book, he outlined not the idea of evolution in general. That was an old concept. In the 17th century, there was a scientific move to tie biological complexity to physical laws, as opposed to species being immutably fixed.

Darwin’s breakthrough was in discovering and describing the mechanisms by which changes in species occur. It wasn’t only described by him alone, though. Most notably, Alfred Russel Wallace came to virtually identical conclusions, which were presented along with Darwin’s in 1858. It was Darwin’s abstract that caught on, and that’s why a good number of the people reading this may not have heard of Wallace.

Darwin’s ideas weren’t perfect and new concepts (like radiometric dating and modern genetics) have given insights that he couldn’t have dreamed of. But he was remarkably forward thinking.

Thomas Henry Huxley, nicknamed “Darwin’s Bulldog,” was a bit more brash than Darwin, and he didn’t shy away from applying Darwin’s theory to the evolution and diversity of humans. In 1871, Darwin published Descent of Man, which expanded his theory to include humans. It’s in this book that he first uses the phrase “survival of the fittest,” borrowed from Herbert Spencer’s perversion of his work in applying his theory to human societies.

I’ll get to exactly why that is perverse a bit later.

First I’m going to separate theory of evolution from the phenomenon of evolution.

I’ve said before that the only thing that scientists do, is say “hey…what’s that all about?” And then they go look at it and figure it out. That’s kind of a lie…because scientists like engineers apply science to create really nifty things like planes, satellites, and bridges. And medical researchers an doctors who apply science to create things like treatments for diseases.

But underlying their work is the science. Engineers work with mathematics and physics, and medical researchers and doctors apply biology. And the underpinning of biology is dun da da daaaaaa—evolution.

Evolution is a phenomena that we observe in nature. From the new flu vaccine to the latest designer dog breed, we can see, anticipate, document, and replicate its occurrence. What science in the time of Darwin struggled to do was explain how that happened.

Natural selection was the mechanism Darwin proposed in On the Origin of Species, which is why the complete title of the work is On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life.

So evolution is the phenomenon best described by the theory of selection.

And going back to “Survival of the Fittest” for a second. In Darwin’s theory, “fitness” refers specifically to “reproductive fitness.” Survive until you’ve reproduced, and nothing else matters as far as nature and natural selection are concerned. That’s why so many diseases can crop up later in life…because individuals pass along their predisposition for them before they manifest.

Given that Darwin was speaking to biological processes, for Spencer to then apply them to cultural constructs as a way to describe why one “race” would fair poorly in a given society is…well…perverse. For Darwin, the “fittest” species is the one that has the most successful offspring who survive to reproductive age, and then successfully reproduce. For Spencer, it has a lot to do with competition for culturally created resources like money and education.

Different kinds of fitness, and without an explicit understanding of both…it’s easy to be a racist pile of garbage if you only get into Spencer.

That said, a good amount of biologists and anthropologists don’t use the term anymore. Because it’s been so bastardized and used to rationalize some pretty horrible stuff, and Darwin himself called the application of Natural Selection to human societies “foolish.”

Anyway.

More recently it was combined with Mendelian and Population Genetics in what’s called the Modern Synthesis, a term coined by Julian Huxley (grandson of none other than Darwin’s Bulldog himself [and with whom my wife shares a birthday!]). This answered some questions that Darwin couldn’t with the material available to him–namely the method of inheritance.

Darwin had some weird idea about something called Pangenesis, in which the body had some particles called “gemmules” that aggregated in an organism and contained the biological information of sexual partners. He thought this would neatly explain why offspring of two individuals could resemble a previous partner of one of them.

This is a good example of a hypothesis. He hypothesized the existence of something, and it was dismissed when found not to be the case. Hypotheses do not graduate to theory until/unless supported by available evidence. Darwin wasn’t always right, and so nobody knows what the heck a “gemmule” is unless you read his other stuff.

The nifty thing about natural selection, is that is perfectly explains how complex, diverse, arbitrary, and inefficient life can be. Why else would animals who are born blind into a world of pitch darkness have eyes that don’t work? Why else would the laryngeal nerve of a giraffe be some 15 feet long, hooping around the aorta, when it could have just went the few inches?

Well…because nature doesn’t care about such details. Survive and have kids. Anything else that works out is gravy.

450px-GiraffaRecurrEn.svg
It’s the same setup in humans, but as our necks are considerably more reasonable, it’s less of a detour.

 

So given these principles, looking back through time with an understanding that humans evolved makes you awful curious. Biological anthropologists are professionally curious in that regard. They study human biology, nonhuman primates, and the fossil record in order to understand the complex evolutionary history we all share.

Biologically, we are primates. Physically, we most resemble other primates, from the great apes to the prosimians. Our biological relation is now backed up and supported by genetic evidence. Sequencing the genomes of the other great apes and comparing mutations, we now know how much genetic material we share with each.

cladogram
A sexy graphic, called a cladogram, neatly illustrates the relationship between different species.

 

Each point of convergence represents common ancestry which, for people like me, who are almost way too excited about evolutionary divergence in our distant past, is what it’s all about.

We have a few ways of coming up with those time frames you see there. When dealing with genetics, it’s possible to look at mutations in the mitochondria, which doesn’t get messed with during sexual recombination. As a result, mutations are less common, and therefore more predictable.

The nifty thing about that, is that geneticists are able to count the mutations in the mitochondrion, and know within a range how much time has elapsed.

Another way is by radiometric dating, which looks at radioactive decay in elements found in stratigraphic layers. We can calculate the rate of decay for one element, observe what element it produces as a result of decay, and in comparing the quantities of the two elements, calculate how long it’s been since that element was laid down in the strata.

The really cool thing about this is that there are multiple methods of radiometric dating, and they jive pretty well with one another and with the genetic dating.

 

With all this, biological anthropologists have incredibly powerful tools to reconstruct our distant past. Using the same idea of tracking mitochondrial mutations, geneticists have been able to reconstruct in a broad sense the migration patterns our ancestors took throughout time until we all reconvene in Africa, where we all share common ancestry.

We can correlate those points of evolutionary convergence on that sexy cladogram I shared earlier using the fossil record, which is growing more complete all the time.

Toumai
Me with my casted replica of Sahelanthropus tchadensis, who lived at the time of our common ancestor with chimpanzees

Owing to the brilliance of the team led by Svante Pääbo, the genomes of Neanderthal has been sequenced, and we now know that our ancestors interbred successfully with them. If you have European ancestry, you’re almost guaranteed to have Neanderthal ancestry. On average, Neanderthal DNA makes up 1-3% of the genomes of people of European ancestry. I know from having my genome sequenced that 3% of me is Neanderthal.

I kind of wonder if I owe my bizarre tolerance to cold to them.

There are (in the United States anyway) four fields within the umbrella of anthropology. Biological anthropology is one of them, and despite spending so much time on cultural topics, it’s the field that drew me to a career in anthropology. It’s a constantly growing field, and so much incredible stuff has been developing in recent years.

Far from Darwin’s understanding of natural selection but with the method of inheritance not yet available to him, both genetics and the fossil record could completely support the theory of evolution in total absence of one or the other component.

And every day, biological anthropologists add more pieces to that puzzle.

I have a degree in anthropology from Rhode Island College. My focus was in biological anthropology but I also have a broad interest in cultural anthropology, archaeology and linguistic anthropology. Pedal Powered Anthropology is an anthropological educational initiative that seeks to bring profound travel experiences to a local level while encouraging others to get out and explore the world around them. This blog details all aspects of my work as Anthrospin, including my take on topics within four fields anthropology as well as bits about a lot of different aspects of culture, primarily race, gender, privilege, the environment and my own personal relationship with anxiety.

1 comment on “Evolution’s Place in Anthropology

  1. Pingback: Meme’s the Word – Pedal Powered Anthropology

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