Paleontology, Paleoanthropology and a more Holistic Understanding of Extinct Species
I spend a lot of time researching and thinking and writing about paleontology (including paleoanthropology). What little work I have done within the field, its implications and its limitations, have shaped my perspectives far more than my time spent in books and classrooms ever could.
From a traditional stand point, paleontology focuses on the fossil record and the contexts in which fossils are found. Initially, there was no way to date discoveries that were found. It was noticed that layers of sediment accumulate and when undisturbed, it can (for the most part) indicate the relative age of something. This is called superposition.
The relative age was (and in some cases still is) the problem. Relative to what surrounds it. The layers above and below. The laundry directly on the floor has been on the floor longer than the laundry directly on top of that. How much longer, who knows. But the stuff on the floor has to have gotten there first if it’s underneath. So, relatively speaking, it’s been there longer.
What if the laundry piles/geological layers get jumbled in whatever earthquakes or floods can happen? Well, we can compensate for that but it’s something I’m not getting into here because it’s not the purpose of this post.
With different methods, we can now date different kinds of rocks and layers by analyzing aspects of the chemical compositions and presence of whatever isotopes. What that means is that we’ve developed methods of dating that are more than just relative. Even though superposition is still critical.
Beyond that, what about what we find? We’ve gotta make sense of it. Fossils and trace evidence like footprints don’t give us the quantity or quality of information about a species that even just looking at a single living individual can.
The bones are fossilized. We can see where muscles attached, we can infer something about the size and locomotion of the animal. But when we find a bunch of fossilized remains, it can be really tricky to determine how many species there are.
I mean…you’re not seeing them reproduce. All we’ve really been able to do is measure them and compare to one another. Sort of like how we’ve been able to with geological superposition. We know, relatively speaking, that this fossil is more or less like this one or that one.
The age of it helps. If something is morphologically (fancy word for anatomical shape) different, in a much older or younger layer, and/or in a much different region it’s probably a different species.
But there is a serious challenge in making the call.
Neandertal, the archetypal “caveman” was for so long considered to be something completely other than human. Some considered them ancestral. Some considered them distant relatives, brutish idiots who were out-competed by modern humans.
And when you look at them, they do look pretty different:
The Neandertal has bigger teeth, a more robust jaw, almost no chin, that weird back of the skull that looks like a duck’s ass. A heavy brow ridge, almost no forehead.
And despite being portrayed as idiotic, their brains were bigger. They made tools. They hunted. They were far stronger than us. They were better adapted to cold. And they persisted for far longer than we have, and in almost as varied of climates.
So…why were they considered so stupid for so long? Because an early reconstruction of a skeleton portrayed them as stooped over and lumbering. Turns out that this was an individual who had advanced osteoarthritis. And had so few teeth it would have been difficult to eat without assistance. And they were of an advanced old age. I mean…old age for Neandertal…so, like 40.
Either way. This is someone who couldn’t eat or get around by themselves. They had to have had help. Help means communication, understanding, compassion. Maybe not exactly as we know it. But it has to have been there for this individual to have survived so long.
These individuals cannot have been as stupid as originally thought.
Well, things have come quite a long way. The amazingly awesome people at the Max Planck Institute for Evolutionary Anthropology have worked out the genome of Neandertal. And they found out that we did, indeed interbreed.
Not only did we interbreed, but people with European ancestry have an average of 1-4% Neandertal DNA.
Me. Personally. I have 3% Neandertal DNA.
To contextualize that. My last name is Lyons. My paternal grandfather’s family is from Ireland. I’m Irish.
My mother’s family name is DeMarino. My great grandmother was from Italy. I’m Italian.
I have 6% each Irish and Italian DNA swirling around in me. That means of what I “am,” it’s not in much higher concentration than DNA from a group long assumed to be of no relation except maybe distant ancestry or offshoot.
The whole thing I’m getting at is that just looking at and comparing different fossils based on their relation to one another can’t give the entire picture.
There are modern examples of similar genetic relationships. There is a phenomenon known as ring species, in which the home range or migratory patterns of related species overlap. Viewed kind of like a clock, 12 can interbreed with 11 and 1, to a lesser extent (maybe with infertile offspring, for example) with 10 and 2, and then not at all with 3 and 9. From 3 and 9, the patterns continue to 6.
That’s a hypothetical explanation, but a good real life example is the Heron Gull, whose migratory patterns overlap in a similar way, and who can interbreed with varying success.
But, if you were to look at their skeletons…you would likely conclude that they were the same species. Even when their genetics say they couldn’t interbreed and even when observations of the species shows the same.
There is another group of crickets. They sing at certain temperatures. They can interbreed without any issue but they’re separated by the fact that they just don’t interbreed…because they sing at different temperatures. They even live in the same area. Slowly, they’re becoming genetically distinct while living in the same area.
So that then begs the question of how we know…how we classify a species when all we have are potentially scant fossil remains.
Nowadays, with living species…a chimp is a chimp. It can’t or wont breed with a turkey. They’re separate species.
There’s no such luxury with the fossil record.
Looking at two relatively similar–or distinctly different–individuals, we can’t really know without more than a morphological analysis. We have moved past just looking at a skull and making a call. Some species have radically different morphology, and it’s a safe bet to say they’re different species.
But modern humans and Neandertal fell into that categorization as well.
I almost hate to share this next image because of racist assholes out there. But check out the differences in these two skulls:
On the left is the skull of an Australian Aborigine. On the right is an Eastern European. If you’re an idiot racist and start trying to use that as proof of differences in the races, keep in mind that you’re an idiot and even if it WERE (it’s not) proof of biological difference, you have no way from the two of them to discern what those differences are or mean or which of the two is more intelligent.
And as an aside, certain studies have shown that when looking at actual intelligence, hunter-gatherers tend to be MORE intelligent than the average Western dork. The reason being is that they’re interactive participants in their environments, while I’m sitting on my couch watching TV, excited for the eggs I’m about to cook once I’m done typing this.
Anyway. My point is that just looking at skulls–or any skeletal remains–can be pretty misleading unless you can really get a lot of information from them.
I did some work as an undergraduate assessing variation in modern primates. Specifically I looked at the bases of skulls, at various soft tissue attachment sites associated with chewing, vocalizations, blood flow to the brain, hearing and even posturing. I measured the skulls of chimpanzees, orangutans, gorillas, silverleaf monkeys and proboscis monkeys. I measured all of this stuff–15 linear measurements and 2 angles.
And I just collected the data. This builds an understanding of how much variation is seen in living species. Once we understand how much is seen in living species, we can have a gauge for what exactly it is we might expect in the fossil record.
I chose the species I chose because they’re primates. They’re apes and also new world monkeys. They’re our closest relatives, and by inference some of the closest relatives of the hominins we dig up out in Africa and whatnot.
I chose the measurements I chose because they’ve been done before. On Homo habilis and Homo rudolfensis. You can see by the names that they’re considered different species. But they’re found in the same areas and same time periods. Time periods again in a relative sense…dating methods aren’t to the day. Even if they’re in the same layer, individuals may have existed hundreds or thousands of years ago and thus never have even met.
Knowing what we know about the pitfalls associate with that Neandertal, and about ring species, we know that that’s often problematic.
So doing some research I found that it’s been demonstrated that variation within primates, while obviously a marmoset is way smaller than a gorilla, the patterns of variation tend to be the same. Building off of that, and given that I have access to measurements done on habilis and rudolfensis I decided to take the same measurements on modern primates.
Take the two species in the fossil record and treat those measurements as a range. Say “ok, these are one group, and every measurement in between them is within possibility for this group, and everything without them is something too big or too small.”
Then I take the modern species and measure a ton of stuff. And find out if the mean measurement has a different range above and below it than the fossil record.
That’s how you see how varied a species in the fossil record is. My study is tiny compared to what needs to be done.
But I also looked at some other things.
I did some work in Kenya in 2013. I’m not going to get into exactly what it was we were up to because that’s someone else’s project and I’m not gonna scoop him. But we collected a lot of fauna, and a lot of it was associated with the same two species–habilis and rudolfensis.
And you know what? They hung out with the same animals.
So I took that same batch of crap and added to it some data published by Thure Cerling, also in 2013. And it agreed with what I found in Kenya.
So that’s three separate kinds of analysis. Morphological–measuring the variations in the base of the skull. Paleoecological–using the associated animals to reconstruct the environment. Stable isotopic–using isotopes of carbon to determine what types of foods an animal ate while alive.
Yeah…it’s all more work. My study included close to 200 skulls. That’s paltry. If I had close to 1,000 I would feel much better. If I had 20 skulls from habilis and rudolfensis I would feel much better. But I don’t.
So I tried to build a better case using concepts and data put forth by other and well-respected scientists.
So yeah, it’s all more work. But I would also argue it’s more understanding, and I would go so far as to argue that it’s much closer to actual and correct understanding.
I’m not novel in this, either. Anthropology has always been a holistic science, and it’s methods were able to discount the notion of race being a biological reality in 1910 (it was ignored). In concept, anthropology as a science takes (or should take) into consideration every avenue realistically possible.
It’s had its fits and starts. But even in biological anthropology, researchers are taking into consideration more bodies of data and more kinds of analysis.
It’s not a novel concept. It’s not my idea at all. But it absolutely is the way forward in understanding our own history and our biological origins as well as the history of life on the planet itself.
Posted on 11/21/2015, in General Science, Paleoanthropology, personal perspectives, Scientific conjecture and tagged anthropology, biological anthropology, human fossil record, human origins, paleoanthropology, primatology, species variation. Bookmark the permalink. Leave a comment.