In 1972, a fragmented but nearly complete skull, as well as several postcranial elements were found in the Koobi Fora region of Kenya. Classified then as the genus Homo, it wasn’t until later that the skull was attributed to its own, brand new species– Homo rudolfensis. Since its discovery and initial description, trying to accurately classify rudolfensis has been a bit of a point of contention among paleoanthropologists. That isn’t a bad thing, though, and by the end of this point you’ll hopefully understand why.
One of the big and tricky parts with correctly placing this critter within the proper species is that though there were several postcranial bits found, they couldn’t definitively be considered to be part of the same individual, or even species. That’s often the case when dealing with such old materials…stuff doesn’t necessarily stay put or intact.
The nearly complete but fragmented skull (cataloged KNM-ER-1470) was reconstructed by the late, great Richard Leakey. He reconstructed the brain case as being slightly larger than earlier species that were classified as Australopithecus, and with a flatter face as well. At the time, this was very contentious because the sediments in which it was found were considered as early as almost 3 million years old. That put them squarely within Australopithecus‘ realm, and also the earliest evidence of the genus Homo, which had some implications for the family tree as a whole.
A fun aside about the specimen name. KNM-ER-1470 is broken down as follows: Kenya National Museum-East Rudolf-the next number in the sequence of cataloged fossils found. East Rudolf refers to Lake Rudolf. Lake Rudolf was renamed to Lake Turkana in 1975, but because we can apparently never quite let go of all shadows of colonialism, we’ve kept it ER instead of changing it to ET.
This was later redated and redated and now sits right around 2 million years ago. That’s much more palatable (and supported by a LOT more direct evidence, not just superposition) as it means it was walking around firmly within the time of our genus, Homo. Late for, but not impossibly australopithecine, Homo rudolfensis was sharing the landscape with others, including Homo ergaster and Homo habilis.
As just a skull, any classification is kind of a tall claim. And so, 1470 has been called rudolfensis, habilis, just Homo with an undetermined species, as Australopithecus, Kenyanthropus, and Pithecanthropus (the latter of which doesn’t exist at all anymore). Alternate reconstructions of the skull have both shrunken and enlarged the brain case, which consensus now plops at 700-750 cubic centimeters. That’s small for Homo overall, but right in line for early members of our genus. It’s also huge for Australopithecus.
As mentioned above, there were a good number of species roaming the African landscape around 2 million years ago. We’ve found a bunch of them, but not nearly all and those we have found aren’t nearly all complete. Even if the relative handful we have found WERE complete, it’s still just a few individuals. And just a few individuals cannot possible represent the total diversity of a species…and that’s the big snag.
Sure, they’re reconstructed, but that in and of itself is tough. You don’t have a clear picture of the finished puzzle. Bones are compressed, warped, shattered, and dispersed in the millions of years since death and during/after fossilization. Close comparisons of similar materials are referenced to understand what could or likely couldn’t be correct. But really it’s like doing an incomplete puzzle you found on the side of the highway in the middle of a rain storm. A lot of the picture is missing, as are many of the pieces. Those that remain aren’t necessarily their original shape. You’ve done a million puzzles, but some of it is still gonna be educated guess. Maybe I’ll try next. Will we come up with the same result?
Now compound that with a couple million years of weather and being trampled and driven over. That’s what we’re working with.
This species lived at the dawn of our genus. We know from observing evolution in real time that it isn’t exactly the “flick of a switch” that separates species, finally and totally. Really, it’s more of a gradation.
Put two drops of paint on a palette and smear. Where does one color end and the next begin? We try and like to deal with clean separations and delineations. Realistically we are dealing with a good deal of overlap in both space and time. Body size, brain size, morphology, habitat, diet, locomotion, age…these all more or less coincide.
Where do we draw the line? To some extent, I’m perfectly happy NOT drawing one. These were similar, coexistent, and closely related species. They competed for the same resources, lived and died in close proximity to one another, and in all likelihood probably got busy with one another. This SHOULD be a hard question to answer. After well over a century of bickering about the Neanderthals, turns out a good amount of humans today have their DNA. Their remains are obviously different than ours. But we could and did interbreed.
I’ve done my own legitimate studies on the variation between these two species and have my own views as to where they fall. But it largely doesn’t matter to me whether they’re lumped into one species or split into two. They lived, died, and essentially founded the lineage that led to me typing this. That we can learn about them at all is simply amazing.