What philosophical significance is there in the now scientifically proven fact that all humans are the same biological organism?

Question

Before quite recently, it was only a belief whether all humans are the same. Before Darwin and even afterward, many people held to polygenism, which posits that humans were descendant from many separate species. Even in more recent times, some humans regarded their "race" superior to that of others, and we all know about slavery, "savages," and colonialism, all of which illustrated such attitudes.

Now, however, these claims have been disproven by DNA analysis, and with the exception of very minor superficial DNA differences among individuals, the overwhelming interpretation by scientists is that we are all the same.

Has this recent fact affected any of the various schools of philosophical thought, and if so, which ones?

Answer 1

Very little.

The biological species concept is of great interest to population biologists and evolutionary biologists and geneticists who need to understand how genes flow through a population, because it is a terse summary of who (usually) reproduces with whom.

But certain knowledge that men and women are of the same species did not deter sexists from devising arguments; nor did even the old slave traders seriously believe that people of different races could not reproduce. They claimed there was something inherently different between people, not necessarily related to reproduction, that justified their actions. Calling their notions "arguments" is charitable - one of the more popular was that one race bore the Mark of Cain based on Biblical imagery, despite the well-known account of Noah's family as the sole survivors in a subsequent catastrophe. Is self-serving dishonesty a philosophy?

Showing that all humans potentially have the same genes doesn't prove they do have the same genes. More relevant is that inheritance of IQ did not turn up in the data the way that most people assumed it would in the 1990s. The "growth mindset" is a vastly more useful concept in education. IQ is a dubious reason to justify discrimination anyway. A racist who claims a ten point IQ gap in a certain data set and calls for discrimination on that basis still won't offer to proxy his vote or donate his labor to someone who scores 50 points higher than he did on a test!

The more relevant phrase is "people are". People are ... what? We need to solve the hard problem of consciousness and then see whether that consciousness is in fact the same. An individual human brain can be split into two parts - are those the same person or different people? If you forget where you left your keys, are you the same person you were when you put them away? The other week for a while I was getting ready for work I needed to do on Wednesday while talking to someone about a vaccination they were receiving on Tuesday. At some point it occurred to me that it wasn't both Tuesday and Wednesday, but was I the same person as myself before that?

The most reasonable guess concerning the question corresponds to the familiar Eastern religious concept of atman, i.e. that consciousness is all one thing. However, believers in those philosophies sometimes greatly deviate from the definition of species, with Jains attempting even to protect microscopic organisms in drinking water. My own guess is that there is a very relevant distinction to be made that is close to the species boundary, accounting for the differences in how humans interact with the world, but proving it is another matter. I would be in any case very skeptical of a position that H. floresiensis or neanderthalensis or even erectus lacked the quality of human consciousness.

Answer 2

No, because just as species diverge, so groups of humans might begin to, in a way that can be used by those who wish to, to preserve historical attitudes - in science the concept of race has been discredited, but is still widely referred to. The rest of my post will address some implications of human evolution that may bear on philosophy.

It seems you mean a common ancestor. There is an increasing case being made that life has emerged multiple times (eg by Paul Davies, who worked on cells with an arsenic metabolism).

Gaia theory and other work of Lynne Margulis around systems biology and autopoeisis present more philosophical issues, with many biologists arguing that these are unfalsifiable, in all except their shallowest implications. In practice, that will depend on astrobiology and the discovery of extra-terrestrial biosystems, which could be as soon as we get to Mars & Io, or be much more difficult - we have discussed evaluating how effective the SETI has been, and the margins for error in evaluating the frequency of life are huge, plus many uncertainties about our own future. The emergence of life on Earth less than 0.2b years after the crust stabilised suggests it be common. But cell nuclei emerging, & intelligent organisms developing, are far harder to evaluate - it may have taken a fine balance if punctuations of equilibrium, for instance.

Homo sapiens went through a long bottle-neck of diversity around 70,000 years ago, linked to volcanic activity in that era. And it's thought trade networks and more complex religious and art practices emerged at that time, which enabled homo sapiens sapiens to emerge eventually as the sole surviving hominid. Continent-wide variations are likely a result of low rates of interbreeding between hominids, neanderthals in the Eurasian North, and denisovans on the Tibetan plateau and beyond. The genes that persist from these groups are primarily about disease resistence; and secondarily skin variations in the North for vitamin D production and tolerance of low humidity (below freezing air is very dry) and altitude tolerance to cross the Tibetan plateau. Many, many questions remain, this information is largely from the last decade; but we can expect more details from DNA. A substantial number of remains from first generation hybrids, seems to be a statistical challenge to the idea interbreeding was rare, for instance.

There remains less variation among all humans, than is found within single breeds of domesticated dogs. This does have implications, culturally if not philosophically, given the biology of race is not a topic for philosophy.

The evidence points to huge plasticity among humans, with our neocortex still developing until age 25, and majorly linked to socialisation. The hijacking of shame disgust and pride have allowed social variation to be focused in the meme-sphere rather than genes. The data for culture influencing genes is very weak, except around food. But we have a lot to learn about how our brains developed.

The importance of the meme-sphere and language as a kind of collective heritable intelligence, is I'd say one of the biggest areas for philosophical development going. Whether genes push culture to develop, or culture pulled genes to get honed, is a major source of tension, and the mechanisms and development of language. And much about the topic and how to understand it is unclear, which requires philosophy for development.