Neanderthals
The following passage is adapted from an article entitled “The Mysterious Downfall of the Neanderthals” (2009 Kate Wong).
- Ever since the discovery of the first
- Neanderthal fossil in 1856,
- scientists have debated the place
- of these bygone humans on the
- family tree and what became of
- them. For decades two competing
- theories have dominated the
- discourse. One holds that
- Neanderthals were an archaic
- variant of our own species, Homo
- sapiens, that evolved into or was
- assimilated by the anatomically
- modern European population.
- The other posits that the
- Neanderthals were a separate
- species that modern humans
- swiftly extirpated on entering the
- archaic hominid’s territory.
- Over the past decade, however,
- two key findings have shifted the
- fulcrum of the debate away from
- the question of whether
- Neanderthals and moderns made
- love or war. One is that analyses
- of Neanderthal DNA have yet to
- yield the signs of interbreeding
- with modern humans that many
- researchers expected to see. The
- other is that improvements in
- dating methods show that rather
- than disappearing immediately
- after the moderns invaded Europe,
- starting a little more than 40,000
- years ago, the Neanderthals
- survived for nearly 15,000 years
- after moderns moved in.
- These revelations have prompted
- a number of researchers to look
- more carefully at other factors that
- might have led to Neanderthal
- extinction. One of the most
- informative new lines of evidence
- bearing on why the Neanderthals
- died out is paleoclimate data.
- Scholars have known for some time
- that Neanderthals experienced
- both glacial conditions and milder
- interglacial conditions. In recent
- years, however, analysis of
- primeval isotopes have enabled
- investigators to reconstruct a far
- finer-grained picture of the climate
- shifts that occurred during a period
- known as oxygen isotope stage 3
- (OIS-3). Spanning the time
- between roughly 65,000 and
- 25,000 years ago, OIS-3 began
- with moderate conditions and
- culminated with the ice sheets
- blanketing northern Europe.
- Considering that Neanderthals
- were the only hominids in Europe
- at the beginning of OIS-3 and
- moderns were the only ones there
- by the end of it, experts have
- wondered whether the plummeting
- temperatures might have caused
- the Neanderthals to perish. Yet
- arguing for that scenario has
- proved tricky for one essential
- reason: Neanderthals had faced
- glacial conditions before and
- persevered.
- In fact, numerous aspects of
- Neanderthal biology and behavior
- indicate that they were well suited
- to the cold. Their barrel chests and
- stocky limbs would have conserved
- body heat, and their brawny build
- seems to have been adapted to
- their ambush-style hunting of
- large, relatively solitary mammals
- that roamed northern and central
- Europe during the cold snaps.
- But the isotope data reveal that far
- from progressing steadily from
- mild to frigid, the climate became
- increasingly unstable heading into
- the last glacial maximum. With that
- flux came profound ecological
- change. So rapid were these
- oscillations that over the course
- of an individual’s lifetime, all the
- plants and animals that a person
- had grown up with could vanish
- and be replaced with unfamiliar
- flora and fauna. And then, just as
- quickly, the environment could
- change back again.
- It is this seesawing of
- environmental conditions that
- gradually pushed Neanderthal
- populations to the point of no
- return, according to scenarios
- posited by such experts as
- evolutionary ecologist Clive
- Finlayson. These shifts would have
- demanded that Neanderthals adopt
- a new way of life in very short
- order. For example, the
- replacement of wooded areas with
- open grassland would have left
- ambush hunters without any trees
- to hide behind. To survive, the
- Neanderthals would have had
- to alter the way they hunted.
- Some Neanderthals did adapt to
- their changing world, as evidenced
- by shifts in their tool types and
- prey. But many probably died out
- during these fluctuations, leaving
- behind ever more fragmented
- populations. Under normal
- circumstances, these archaic
- humans might have been able to
- bounce back, as they had previously.
- This time, however, the rapidity
- of the environmental change left
- insufficient time for recovery.
- Eventually, the repeated climatic
- insults left the Neanderthal
- populations so diminished that
- they could no longer sustain
- themselves.