|Evolution in the News - May 2017|
|by Do-While Jones|
Where does Homo naledi fit in the human evolutionary tree?
We told you about Homo naledi in our October, 2015, newsletter. 1 At the time, evolutionists didn’t know how Homo naledi fit in their fictional evolutionary tree. Now they claim they may know. New Scientist provides you with this excellent background summary.
In 2013, Lee Berger at the University of the Witwatersrand in Johannesburg and his colleagues made an extraordinary discovery – deep inside a South African cave system they found thousands of bones belonging to a brand new species of early human — and now we finally may know when this species lived and how it fits into our evolutionary tree.
By 2015 it was becoming clear that the new species, which was named Homo naledi, was unlike anything researchers had discovered before. Although parts of its skeleton looked identical to our modern human anatomy, it had some features that were strikingly primitive – including a skull that was only slightly larger than that of a chimpanzee.
But Berger and his colleagues had trouble establishing how old the H. naledi fossils were. Without that piece of information, most other researchers agreed that the true significance of H. naledi for understanding human evolution was unclear. Guesses have varied from as old as 2 million years to as young as 100,000 years. 2
Evolutionists tend to believe that just because one species is younger than another, the younger species must have evolved from the older species. This is foolish because there is more to it than just chronology. George Washington obviously can’t be a descendant of Abraham Lincoln because Washington was born before Lincoln was; but the fact that Abraham Lincoln was born later doesn’t necessarily prove he descended from George Washington. There must be some sort of evidence of ancestry in addition to the chronology.
Chronology alone can’t prove an evolutionary theory—but chronology can disprove a previous theory (if the new chronology is believed). Because one can’t propose a new evolutionary theory without first disproving the previous one, one has to come up with a new chronology. That’s why chronology is so important to evolutionists.
New Scientist acknowledges the difficulty in dating fossils.
Why has it taken so long to establish the age of the fossils?
It can be surprisingly difficult to work out how old fossil bones are. Many of the techniques researchers can use require the isotopic analysis of bone samples. Berger and his colleagues are reluctant to use these techniques, because they involve destroying small samples of precious fossil material.
Another option is to date the rock or sediment that blankets the layer in which the fossils are found. Ancient lava flows, in particular, contain chemical signatures that are perfect for isotopic dating. But the H. naledi remains were found in a cave in which there were no easily dated sedimentary layers covering the fossils.
Researchers can also work out the rough age of the fossils by looking at the fossil remains of other species found alongside them, if the age of those other species has already been established. The cave in which the H. naledi fossils were found contains virtually no bones from other species, though, making this approach a nonstarter. 3
They found 1,550 H. naledi fossils. Surely they could have destroyed one unremarkable fossil to do isotopic dating on it if they had wanted to. Carbon 14 dating could tell if these bones are less than 5,000 years old, and came from modern humans, but they would not have wanted to find that out. They wanted these fossils to be 200,000 to 300,000 years old. There would be nothing to gain from learning that these fossils are 1,000 years old (for example) so why ask the question if you are afraid of what the answer will be?
In this case, there were no other fossils of “known age,” so it wasn’t tried. If there had been other fossils, dating the H. naledi fossils by ages of other fossils in the same layer would depend upon the unverifiable assumption of the age of those other fossils.
So how did Berger and his colleagues work out the age of the fossils?
We don’t know yet. The scientific papers in which this information will be revealed haven’t been published. The National Geographic interview mentions that Berger and his colleagues have found a second cave chamber containing more H. naledi remains – perhaps these additional fossils were preserved in a context that made dating less challenging. 4
They don’t know how the fossils were dated, but they report the new ages (300,000 to 200,000 years old) and ponder what that means.
If the fossils are 300,000 to 200,000 years old what does that mean?
Our earliest hominin ancestors lived at least seven million years ago. The first species to look a little like modern humans appeared between about two and three million years ago.
But our own species – Homo sapiens – evolved about 200,000 years ago.
So, if H. naledi lived 300,000 to 200,000 years ago that’s a remarkable discovery.
It means that a species of human with some surprisingly primitive features – including a tiny skull and brain – survived into the relatively recent past. Conceivably, H. naledi might even have met early members of our species, H. sapiens. One could even speculate we had something to do with it going extinct. 5
The headline of the article included the phrase, “why that matters.” Why does it matter?
It probably depends on whom you ask. Based purely on its strange anatomy, H. naledi seems to belong somewhere near the very base of the “true human” family tree – an idea suggested in some studies of the fossils.
But we know that the first early humans appeared more than two million years ago. If H. naledi is just 300,000 years old, some researchers might argue that it can’t belong to the base of our family tree. It’s too young. Perhaps it even had a modern-looking ancestor and later evolved primitive-looking features.
But it is, in fact, still perfectly possible that H. naledi really does belong somewhere near the base of our human evolutionary tree. The species might have evolved more than two million years ago, as one of the earliest “true” humans, and then survived, unchanged, for hundreds of thousands of years. 6
The age of the fossils is important because if they are two million years old, they are the “earliest true humans.” But, if they didn’t evolve until 200,000 years ago, there are older human ancestors (if the dates of those ancestors are correct). But, maybe, the first H. naledi really did evolve two million years ago, but didn’t evolve any more for 1.8 million years, when these particular H. naledi individuals died in the cave where they were found. They just don’t know.
But that doesn’t answer the question, “Why does it matter?” The true answer is, “It matters because the controversy is justification for further research—and that requires more funding.”
We are reasonably confident that you remember Neil Armstrong was the first man to walk on the moon. We would be surprised if you remember who the seventh man to walk on the moon was. Being the seventh man on the moon wasn’t as newsworthy as being the first.
In the same way, nobody cares about the seventh-oldest dinosaur discovered. There is an understandable desire for paleontologists to find a dating method that proves their discovery is the oldest (or youngest) ever found. Finding the oldest something-or-other changes what was previously believed about evolution, and makes the discoverer important because he set the record straight!
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Disclosure, October 2015, “Homo Naledi”
2 Colin Barras, New Scientist, 25 April 2017, “Homo naledi is only 250,000 years old – here’s why that matters”, https://www.newscientist.com/article/2128834-homo-naledi-is-only-250000-years-old-heres-why-that-matters/