Human Origins Part 3: The Fossil Record, and Other Lines of Evidence

hominid

بسم الله الرحمن الرحيم، وصلوات الله وسلامه على أشرف المرسلين

In the name of God, Most Gracious, Most Merciful.

Check out part 1 here if you haven’t already, which was an intro to this series of posts, and part 2 which is about human-chimp similarities. In this post, I’ll discuss the fossil record, population genetics, evolutionary psychology, and human-neanderthal mating.

The Fossil Record

There’s a lot that can be said about the fossil record. I’ll try to be as brief as possible. Basically, any honest scientist will admit that the fossils don’t really reveal much. We have a bunch of fossils of ape-like creatures, and some old fossils that look like humans, but it does not show a transition from ape-like to human-like forms.

This is admitted by the Smithsonian website, but they use weasel words and try to brush aside the issues. Here’s a quote:

While the existence of a human evolutionary family tree is not in question, its size and shape – the number of branches representing different genera and species, and the connections among them – are much debated by researchers and further confounded by a fossil record that only offers fragmented look at the ancient past. The debates are sometimes perceived as uncertainty about evolution, but that is far from the case. The debates concern the precise evolutionary relationships – essentially, ‘who is related to whom, and how.’

So they don’t know who’s related to whom and how, but they think it’s “not in question” that they are related. Not sure what planet they’re living on, but in real life, you need to be able to answer these questions in order to have confidence in a theory. Otherwise the whole thing is just wild speculation based on almost no evidence. If someone came up to you on the street and claimed to be your relative, wouldn’t you ask them: “how exactly are we related?” It’s common sense.

We can also point to specific gaps within the alleged history of human evolution. Some examples: Australopithecus appears suddenly without any clear ancestor form, there’s a million-year-long unbridged gap between Australopithecus and the earliest Homo fossils. In addition, Homo sapiens itself appears abruptly with radical changes and without any transitional forms, as the block quote below mentions.

These “missing links” are acknowledged by scientists in the field, even if popularizers of evolution deny them. What’s shameful about it is how in history, racist theories have been used to fill in the gaps. One idea was that Africans are a link between us and lower primates. Others have put Jews, Roma, and others in the gap, sometimes as part of a racial hierarchy which shows a spectrum starting with the Western European white man and ending with apes. An example of evidence used to support these theories was the study of skull shapes, known as phrenology. Of course, such theories are discredited now. But the reason they were abandoned has more to do with ethical reasons, because they influenced chattel slavery and the Nazi Holocaust, than compelling scientific evidence one way or another.

I want to focus on Homo sapiens specifically. According to fossil dating, the first Homo sapiens appeared around 200,000 years ago, but this appearance was sudden and unexpected. I found these quotes from an expert describing what happened:

Our species, Homo sapiens, is highly autapomorphic (uniquely derived) among hominids in the structure of its skull and postcranial skeleton…

[The arrival of Homo sapiens] was apparently short-term because it is essentially unanticipated in the fossil record…

Morphologically, our living species H. sapiens is extremely distinctive…

Available evidence thus now strongly suggests that the wide, flat, heavy pelvic morphology is indeed primitive for the genus Homo, in which case, the basic body form of H. sapiens, as well as that of its skull, is highly derived…

Given the radical departure in cranial anatomy of these early African H. sapiens from other hominids known in the same time range, from the same continent (there is very little relevant postcranial record, if any), one reasonable conclusion is that the new morphology already exemplified at Herto and Kibish arose in a single change in gene regulation, with cascading developmental effects throughout the body.

In other words, what he’s saying is: Homo sapiens are very different from the other hominids. These changes are not led up to by a series of Darwinian adaptations. So, we can say that a single change led to this radical reorganization.

That’s probably close to the best Darwinian Evolution can do, or any fully materialistic account of human origins for that matter. We might even accept that as a valid scientific hypothesis. But is it capital-T True? It’s hard to wrap your head around it. The most we can say is that it could be possible. But has it been proven to be true? No way.

Takeaway: the human evolution fossil record is so muddled that the best we can do is believe that Homo sapiens came about in a single radical change. Nothing in human evolutionary history can be conclusively proven.

Other Alleged Lines Of Evidence For Human Evolution

Like I said, I’m not claiming to “disprove” human evolution. I’m merely claiming it hasn’t been proven beyond a reasonable doubt. The main arguments claimed to be in its favor, which I mentioned above, are not enough to prove it with certainty. But there are a few other lines of evidence some people claim to bring, and I’ll deal with them briefly in the following sections.

Population Genetics Models

This topic has received some attention in recent years and months. The idea is that according to pro-evolution scientists, we can rule out the possibility of humanity having descended from Adam and Eve, because humans are too genetically diverse to have come from a single pair. Rather, they say, we evolved from a previous ancestor species through a gradual process, and the population of (proto-)humans never went below a few thousand individuals.

The problem with this theory, of course, is in the assumptions. When the scientists run their population genetics simulations, they assume a certain mutation rate, childbirth rate, average number of partners, and so on. They also assume a “steady-state” population model, in which beneficial mutations spread to everyone else and detrimental mutations are not passed on.

If you change the assumptions, you can get entirely different results. We can use an “explosive-growth” model to simulate early humanity, rather than a “steady-state” model. Assume that all mutations/variations are kept early on, because everyone mates and has lots of kids. If you do this, you’ll find that the current human genetic diversity is compatible with having descended from a single pair.

Again, this does not disprove the idea that we could have evolved from a population that never went below a few thousand, nor does it prove that we’re descended from two individuals. I need to reiterate this so my argument isn’t misunderstood. In this section, I’m merely saying that the claim that population genetics disproves descent from two individuals, is weak and rests on many invalid assumptions.

For more information on this topic, check out this summary of a discussion between two scientists on it, with links to blog posts and research papers.

Evolutionary Psychology

Much of this is merely interpreting human behavior in light of evolution, so it can’t be used as proof for evolution, because that’s circular reasoning. Plus, there’s the issue that applying evolutionary theory to our cognitive skills should undermine our confidence in them, because evolution is about adaptation for survival not discovering truth. Thomas Nagel has talked about this problem in more detail.

Also, a lot of it is just anecdotes. Evolutionary psychologists look at some trait or characteristic that exists in modern-day humans, and ask how this might have created a selective advantage for our alleged ancestors, i.e. made them more likely to pass on their genes. The problem is that anything and its opposite can be said to provide an adaptive advantage in some situation.

The classic example of this is cooperation vs competition, which are opposites. Cooperation is advantageous because when people work together, they all succeed. Competition gives an evolutionary advantage because resources are scarce and you’re more likely to succeed if you hoard them for yourself. So both can be said to be more likely to be passed on, despite being total opposites. As Noam Chomsky famously said, “Just about anything you find, you can make up some story for it.”

Here’s an interesting article on this topic. It’s about a scientist who wanted to get hard data to base evolutionary psychology off of, rather than speculative stories, so he analyzed monkey behavior and tried to build his theories from that. The data simply wasn’t there, so he fabricated evidence. A cautionary tale for all.

In conclusion, nothing produced by the field of evolutionary psychology can be considered evidence for human evolution.

Mating With Neanderthals

According to scientists, many humans have Neanderthal DNA in their genes. So at some point, humans must have mated with Neanderthals, or one of the two raped the other. This seems to contradict the Abrahamic religions’ account of descent from Adam and Eve. However, it’s not necessarily in contradiction, because it has two possible explanations:

  1. The Neanderthals were merely a specific race of humans. In other words, they were intelligent, had free will, and will be held responsible for their actions before God. The evidence in support of this is that generally, it’s not possible for two creatures to mate and produce a child unless they’re from the same species.
  2. Neanderthals were non-human animals, and the DNA in common has a functionalist explanation. For example, let’s say the Neanderthals had a certain hair type or color, and certain humans have the same hair type or color, they would have that DNA in common with Neanderthals and not with other humans who have different hair. This is a totally random example which I’ve just made up, but it illustrates the point.

The overall trend should be clear. Assumptions, speculation, extrapolation, et cetera. No clear-cut evidence that actually proves common descent beyond a reasonable doubt. If one were to accept all of the assumptions, perhaps human evolution could be accepted as correct. But it’s not necessary for someone who doesn’t share the assumptions to believe in it.

Check out part 4 here.

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