A Work of Hope - Feral: Rewilding the Land, the Sea, and Human Life - page 136

as a result of warming and the habitat changes this caused, it is likely
to be less suited to the current climate than those which may have
been hunted to extinction. This is why I have judged the reindeer and
horse harshly: they returned to Britain soon after the glaciers retreated,
but disappeared as the grasslands of the cold, dry Preboreal period
that followed gave way to forest.
We cannot always be sure which factor was most important in the
disappearance of an ancient species. Some of them would have been
affected by both climate change and hunting. So we must make edu-
cated guesses, comparing the survival of the horse and the reindeer, for
example, to that of other hunted species, such as the moose, the aurochs
and the red deer, which lasted much longer. The question of whether
horses and reindeer disappeared because the grasslands turned to forest
or the grasslands turned to forest because horses and reindeer disap-
peared is also hard to resolve. But even those who conducted the research
proposing that the northern Siberian steppes turned to tundra because
the grazing animals were killed by hunters suggest that the southern
steppes turned to forest for climatic reasons.* Nor do we have definitive
extinction dates, as the fossil record is far from complete.
My aim here is to expand the range of what we consider possible,
to open up the ecological imagination. That requires some under-
standing of palaeoecology. The fact that sometimes eludes biologists
and naturalists, steeped in the present, is that every continent except
Antarctica possessed a megafauna.
When I studied zoology at university, I read a number of accounts,
founded on ecology and physiology, which tried to explain why very
large animals live in the tropics but not in temperate nations. I found
them interesting and in some cases persuasive. But, like the authors
of these speculations, I had missed something. The inherent difference
they sought to explain did not exist. Until very recently, large animals
lived almost everywhere, often in great numbers. They could do so
* Zimov et al maintain that 'boreal forest expanded northward at the end of the
Pleistocene into areas that had been predominantly steppe, presumably in response to
climatic warming'. 46 Elsewhere Zimov writes: 'In the southern steppes, the situation is
different. There, the warmer soil allows for more rapid decomposition of plant litter
even in the absence of herbivores.' 47