From “Climatic Fluctuations Drove Key Events in Human Evolution, Researchers Find” ScienceDaily (Sep. 26, 2011), we learn:
Following the onset of high climatic variability around 2.7 million years ago a number of new species appear in the fossil record, with most disappearing by 1.5 million years ago. The first stone tools appear at around 2.6 million years ago, and doubtless assisted some of these species in responding to the rapidly changing climatic conditions.
Actually, tools are handy whether the climate is changing or not. Depending on the direction of the change, so are ear muffs, mitts, and mukluks.
“By 1.5 million years ago we are left with a single human ancestor — Homo erectus. The key to the survival of Homo erectus appears to be its behavioural flexibility — it is the most geographically widespread species of the period, and endures for over one and a half million years. Whilst other species may have specialized in environments that subsequently disappeared — causing their extinction — Homo erectus appears to have been a generalist, able to deal with many climatic and environmental contingencies.”
But what environments subsequently disappeared? A large variety of ecosystems exist today, most inhabited by humans.* What ecosystems existed two and a half million years ago that don’t exist today, such that we can explain human extinctions?
Dr Grove’s research is the first to explicitly model ‘Variability Selection’, an evolutionary process proposed by Professor Rick Potts in the late 1990s, and supports the pervasive influence of this process during human evolution. Variability selection suggests that evolution, when faced with rapid climatic fluctuation, should respond to the range of habitats encountered rather than to each individual habitat in turn; the timeline of variability selection established by Dr Grove suggests that Homo erectus could be a product of exactly this process.
Who knew that “evolution, when faced with rapid climatic fluctuation, should respond” to anything at all? Are we not supposed to quit seeing it as an agent with a purpose?
And as for “Homo erectus could be a product of exactly this process.”? Yes, or of space alien intervention or virgin birth.
Face it guys, this isn’t science. But it’s fun.
* The colder and dryer the climate, the lower the human population density. But, unlike the space aliens, they are really out there. The graphic above is the flag of a real place. Click on it if you like.