The fossil record is full of anomalies (things that deviate from what is standard, normal, or expected) and this is especially true when it come to the fossil record of modern humans and our ancient ancestors. The latest anomaly to arise surfaced earlier this month in Ethiopia when it was announced that a grad student from Arizona State University working on a dig discovered the oldest modern jawbone every found 2 years ago.
It is believed that the fossil jawbone comes from close to the time that the Homo genus (modern man) split away from our more ape-like ancestors with the best known of those being the infamous “Lucy.” The jawbone fossil has been dated at 2.8 million years old thus pushing back the fossil record of the Homo genus by roughly 400K years. The fossil was actually found TWO YEARS AGO near where the fossil remains of “Lucy” were found.
Mainstream anthropology holds that our species, Homo sapien sapien, are the sole surviving members of our kind which may or MAY NOT be the case, frankly. The jawbone was discovered by Chalachew Seyoum who is an Ethiopian grad student at ASU. At this point it is not clear if the jawbone came from a known early species of the Homo genus OR if it comes from a new species of the Homo genus.
So what’s the anomaly? Well it seems that this fossil jawbone has some combined features. That is to say that the hominid it came from had primitive features such as chin shape mixed with some more modern features such as slimmer teeth unlike the large molars found in Lucy’s kind. Lucy comes from the Australopithecus genus by the way and not the Homo genus.
So this jawbone exhibits both primitive and modern characteristics but it is NOT the first that has demonstrated such mixed traits as, in fact, several fossil remains have been found that have a mixture of primitive and modern features. Could this jawbone be from a “transitional” species of the Homo genus? A “missing link” perhaps? Well that is possible based on the mixed features but right now all we have is a jawbone and no skeleton so before I’d say it is a “Missing Link” I’d have to see more remains of this creature.
Finding ancient human ancestor fossils with mixed (primitive and modern features) is not uncommon but there is also another anomaly we need to consider here. Sometimes we find fossils of ancient human ancestors that seem out of place. That is, we find fossils of a more archaic (primitive) form in sediment above fossils that have more modern features. How do we explain this? How could a more archaic ancestor live AFTER a more modern one? And the mixed features seen in this jawbone with BOTH archaic and modern features? It all seems a bit odd but there is a possible explanation.
When we think of evolution, in this case human evolution, we tend to think of a linear evolution. That is, the archaic species of human ancestors were replaced with more modern ancestors and the old became extinct. However, the fossil record seems to indicate that is NOT the case at all. We now know that various species of ancient human ancestors coexisted and sometimes for long periods of time. Evolution, thusly, is NOT linear at all and human evolution is NOT a tree of upward progression but a very twisted bush!
But, getting back to the jawbone with mixed features (archaic and modern) and finding more archaic remains atop more modern remains we MUST consider a possibility. I’d say new possibility but some early paleontologists suggested it or suspected it so, so it’s really not new. And what is that possibility? I prefer to call it HYBRIDIZATION or interbreeding! Dr Susan B. Martinez expounds on this theory in her book “The Mysterious Origins or Hybrid Man” which I am currently reading. She picks up on the theory where early anthropologists left off and presents a case that is plausible in support of the Hybrid Hypothesis.
Looking at these anomalies through the lens of the Hybridization Theory the answers to these two anomalies would be thus:
The reason we find ancient human ancestor fossils with mixed features (archaic mixed with modern features) is due to interbreeding between two different species of human ancestors who coexisted at the same time and in the same place. The mixture of archaic (primitive) and more modern features may indicate “retrobreeding.” That is, a more modern ancestor interbred with a more primitive ancestor. Call it “back-breeding” if you like.
And what about the anomaly of finding more advanced human fossils in lower layers of sediment with primitive ones on top? Finding more primitive fossils on top of more modern ones in more recent sediment doesn’t make sense as what we should find is more modern remains atop more primitive remains. But, that’s not what happens in some cases as we find just the reverse. So what is the answer to this anomaly? Again, hybridization or back-breeding if you prefer!
Interbreeding a more archaic species with a more modern one explains both of these phenomena! Don’t get me wrong, in reading Dr Martinez’s book I do NOT agree with everything she says but her ideas concerning retrobreeding I DO agree with and frankly I think she’s hit the nail on the head.
Let’s face the FACT here and do so bluntly……..
Man is a SEXUAL creature! Much of our behavior is motivated by sexual gratification. Further, SOME among our kind will have sex with just about anything. Consider perversions such as bestiality, etc. We don’t really want to talk about all those perversions but it doesn’t change the FACT that they happen today in our 21st century and I strongly suspect they also happened in the remote human ancestral past! Sexual desire and fulfillment is one of the strongest motivators of being human today and it’s always been so even in our remote past when our ancient human ancestors were running to and fro.
I’m sure you’ve heard that modern humans share about 98% of our DNA with Chimpanzees. However, we share even more DNA with Bonobos! Bonobos are a species of chimpanzee and they are very sexual in their behavior. In fact, they use sex to settle conflicts and alleviate stress and that sex is both heterosexual and homosexual and does not recognize age as a factor. Likewise, to an extend, I think humans often use sex to alleviate stress, resolve conflicts, or simply just for recreation as well as procreation. My point is this:
In remote times there were not many ancient human ancestors running around. We have 7 billion people on the Earth today but in prehistoric times we’re lucky if there were a million or half a million! Various species of human ancestors were living at the same time and in the same areas (coexisting) and so why wouldn’t they interbreed if for no other reason that to continue the species? Without procreation none of us would be here today. The human lineage would have gone extinct long, long ago. Maybe these ancient ancestors interbred sometimes because there was no suitable mate among their own species. Or maybe there wasn’t anyone of the same species around to mate with but plenty of archaic species to mate with. What would you do?
Finding human ancestral fossils with a mixture of archaic and modern features is not uncommon. Finding more archaic remains atop more modern remains is also not uncommon. What we need to begin to realize is that human evolution is not a linear evolution of progression from archaic to modern but that it is a mixed evolution with many ups and downs (progressions and retrobreeding). It’s, as I say, a VERY twisted bush!
The Hybrid Theory also explains why we see various archaic features in humans today that I’ve spoken of before. Why do we see Neanderthal features in some modern humans today and some of whom even have the characteristic bun at the back of the skull? Why can we see browridges in some people reminiscent of Cro-Magnon or Homo erectus? It is because, as Dr Martinez suggests, WE ARE ALL HYBRIDS!
So, without beating the horse to death here’s what I think happened in terms of Human Evolution…………………………..
Several species of ancient human ancestors coexisted some for short periods of time and others for longer periods of time. Think H. erectus coexisting with Neanderthal and archaic H. sapiens (Cro-Mags). These various species interbred sometimes with some breeding with more archaic species and more archaic species breeding with more modern ones. Basically what the offspring are, then, were MUTTS! These offspring were bigger and stronger than their parents and they had both modern and archaic features in their morphology and that’s why we find fossils like the jawbone from Ethiopia with mixed archaic and modern features. AND that is also why we find archaic fossils ABOVE more modern ones in some places! The offspring were hybrids and it is from those hybrids that WE came and that makes us all HYBRIDS or MUTTS!
Now don’t think the term “mutt” is offensive because it’s not. Consider dog breeding. Pure breds tend to be weak and have many problems while mutt dogs tend to have less problems and be stronger survivors. Which would you rather have as an offspring. One that is weak and vulnerable to every disease that comes along or one that is strong with a strong resistance to any disease that comes along? The Mutt is the SURVIVOR not the pure bred! The human species survived because we are those mutts! The pure breds died out and went extinct! Natural selection made this so. Natural selection chose the mutt over the pure bred and that is why we are here today. The pure breds are gone into extinction but all of us “mutt people” are still here continuing onward the human species!! So be PROUD you’re a mutt because it means you are a SURVIVOR!!
Finds like this latest jawbone find from Ethiopia call in to question the mainstream theories of human evolution. It’s time to ADJUST those theories so that they are more in line with the ACTUAL fossil record. It’s time to see human evolution not as a linear evolution but as a mixed bag or progression AND regression. If we don’t begin to revise our concept of evolution then we are continuing to miss the boat. Everything about that “boat” says our evolution has NOT been altogether one of progression but a mixed bag of progression and regression, back-breeding, retrobreeding, ups and downs. In short HYBRIDIZATION! Further, when we look at the fossil record from the viewpoint of the Hybridization Theory suddenly it all makes sense and the questions are answered such as why we find primitive fossils atop more modern ones and why we find fossils such as this jawbone with a mixture of primitive and modern features. Suddenly, human evolution is NOT a mystery but a mixed bag that brought us to where we are today in this 21st century.
Finally, you will notice at the end of the reference articles below that another team reported that the lower jaw from a H. habilis specimen turned out to be more primitive than thought. That’s true but some also show more modern features too. Again, this is the product of hybridization in my opinion.