When did we become human?

Hi guys, I'm a big fan. I started listening about two months ago and I'm finally caught up after binge-listening to the podcast on my way to work. I'm really impressed by your level of analysis and I'm looking forward to many more years of podcasts (I'll get to contributing on Patreon one of these days). I was especially impressed by your episode on "The Changeling" - I think you puzzled out the religious iconography behind the story and I'm hoping you'll consider publishing your ideas in print somewhere.

I think you missed something in your latest episode of the podcast ("V.R.T. - Part VI - Discussion," from 16 April 2019) when you were discussing the length of human prehistory. You said that the numbers that V.R.T. mentioned, a million years and 10 million years, were too large. Here is the passage (Sorry, I only have the Kindle edition to hand, where it is on p. 246):

"How long was human prehistory on Mother Earth? A million years? Some would say ten million. (Bones of my fathers.)"

You noted that our species (Homo sapiens) is about 200,000 to 300,000 years old and our genus (Homo, dating back to Homo erectus) is about 2 million years old. Based on these numbers, you weren't sure why V.R.T. used a million years and 10 million years. Wolfe clearly knew something about prehistory - I am thinking particularly of the bones that Aunt Olivia, Professor Peacock, and Den find in the cave in Peace; the archaeologist in "Trip Trap;" and Wolfe's name-checking of Windmill Hill Cave, Les Eyzies, Altamira, and Lascaux in "V.R.T." So what gives?

The ages that you cited are according to our current (2019) understanding. You have to remember that ideas about human evolution were very different in the late 1960's and early 1970's when "V.R.T." was written. (Full disclosure: I'm a paleoanthropologist who studies skull evolution, so if any of this sounds overly pedantic that's because it undoubtedly is):

Evidence for a 10-million-year span for human prehistory: There was a window of time between the 1950's and mid-1970's where Ramapithecus, a 15-million-year-old species found in India and Pakistan, was thought to be the ancestor of modern humans. According to Elwyn Simons and David Pilbeam (disclosure: my advisor's advisor and his advisor), Ramapithecus had a "U-shaped" dental arch, small canine teeth, and thick enameled-molar teeth, all characteristics that we share with this species but chimpanzees and gorillas do not. Already in the early 1960's nascent genetic data seemed to show that modern humans and chimpanzees shared a unique common ancestor about 6-7 million years ago, which was the first hint that something was wrong with Ramapithecus. Most anthropologists rejected the implications of genetic data until, in 1976, David Pilbeam found a partial cranium with a more complete and undistorted palate and upper teeth close to where the initials remains of Ramapithecus were discovered. It showed that the original distorted palate was reconstructed incorrectly into the "U-shape," when it really should have had parallel tooth rows. Because of taxonomic priority, Ramapithecus has now been subsumed in the genus Sivapithecus, which is clearly related to the modern orangutan and is not a direct human ancestor. Sivapithecus does have thick molar tooth enamel (but so do orangutans) and small canine teeth (a peculiarity, for sure).

Another possibility: In the 1960's, Piltdown Man still cast a shadow over popular ideas about human evolution, and I'm wondering if this also had an effect on Wolfe's estimates for the length of human prehistory. Piltdown was an orangutan mandible (lower jaw) fit onto a modern human cranium and found in "context" with Pleistocene mammal fossils and stone artifacts. Whoever perpetrated the hoax filed the orangutan teeth down to look more like human teeth, and broke and weathered parts of both pieces so that there was no clear point of contact where similar teeth could be compared to one another. With a large (really, a human) brain, Piltdown seemed to support the idea that human brain size evolution preceded the invention of tools or even bipedal walking. New historic evidence convincingly shows that Charles Dawson, the amateur paleontologist who "discovered" Piltdown in 1932, perpetrated the hoax. What is incredible about all of this is that the scientific community built a whole framework for human evolution that held fast for 20+ years in the face of mounting evidence from Africa and Asia (in the form of Australopithecus africanus and Homo erectus, respectively) that bipedal walking and tool making evolved before big brains.

Evidence for a 1-million-year span for human prehistory: In the late '60's/early '70's, the dominant idea about how evolution occurred during the Pleistocene was that Homo erectus gradually evolved into Homo sapiens, maintaining a sufficient degree of gene flow to keep the whole thing together in one species or, at worst, one evolving lineage, through anagenetic change. This ideas was referred to as multiregional evolution. The other idea, more widely-accepted nowadays, is that modern humans evolved in Africa 200-300,000 years ago and migrated out more recently, replacing archaic peoples living in Asia (like H. erectus) and Europe (like Neanderthals). This idea has been referred to as the 'Garden of Eden hypothesis,' the 'Single Origin Model' (SOM), 'Recent African Origin,' or simply as the 'Out of Africa hypothesis.' Recent (last 10-15 years) genetic data shows that, while the SOM is largely correct, there was some degree of interbreeding between modern H. sapiens and archaic peoples like Neanderthals in the Near East and Denisovans and another one or two hominin lineages in Southeast Asia. All the above is to say that a commonly-cited "starting point" for the multiregional evolution of modern humans in the late 1960's was 1 million years, the value that Wolfe used in the above quote.

I guess all of the above is to say that Gene Wolfe knew what he was talking about, human prehistory-wise. Ideas have just changed drastically since he wrote "V.R.T." in the late '60's/early 70's.

Finally, I'd like to quibble a little with something you said about only H. sapiens being "human," and what we refer to as "human" generally. Because of my job this is something I think about quite a lot. As you noted in your podcast many times, this is something that Gene Wolfe contended with in his work, but instead of the word "human" he often used the word "people," as in this quote:

"They weren't really people you know, just animals shaped like people." ("V.R.T.")

I think you'd both agree that there is a case to be made (and Wolfe makes that case) that the abos are people because they behave like people - that is, human behavior is what makes people "people." One of the main themes in Wolfe's work is that robots, aliens, human-like animals, etc. can be "people" ("human"). Now the truly pedantic part: I wouldn't restrict the term "human" to just Homo sapiens. Does that mean that Neanderthals weren't "human." I started with an easy one, since Neanderthals are so like us, and most of us carry some of their genetic material. How about Homo erectus? Homo habilis? Australopithecus afarensis? Ardipithecus ramidus? Even I have to start double-guessing myself by the end of this short list because it is hard to pin down what characteristics make us "human." This is a question that a lot of scientists struggle with, and there are no definite answers. There is a Society of Catholic Scientists conference June 7-9 at University of Notre Dame, for example, where the theme is "What does it mean to be human?" (I'll be there, presenting a poster that includes some of what is in the above paragraph).

Keep up the good work! I'll try to keep future epistles to a more reasonable length.

- Rob McCarthy