Monsters We Met - In balance with nature?

Some scientists think humans eradicated large animals, known as megafauna, after they migrated from Africa around 100,000 years ago.

The 'overkill' hypothesis holds that megafauna (animals with an adult weight greater than 44kg) vanished only a few centuries after the arrival of man.

Humans coexisting with megafauna

Opponents of the overkill hypothesis point to a variety of evidence that human hunters were not the culprits. Their arguments against humanity as killers are:

• long periods of human-megafauna coexistence
• little evidence of hunting
• people were hunting the wrong species

For the overkill hypothesis to hold true, prehistoric humans must have killed off the megafauna very rapidly - within 1,000 years of arriving in a region. If the extinction happened more slowly than this, it wouldn't have been true overkill. More to the point, it may be impossible to pick apart all the interrelated factors (hunting, climate and competition) that would have played a part over a longer period.

Europe

Long periods of human/megafauna coexistence

Homo sapiens arrived in Europe about 40,000-43,000 years ago, but species such as the woolly rhino and the cave bear did not become extinct for another 28,000-30,000 years. If human hunters were responsible, they were remarkably slow and inefficient.

People were hunting the wrong species

Where humans kill high numbers of animals, their prey often turns out to be species that survive, not those they are accused of hunting to extinction. This is true of reindeer and red deer in ice-age Europe. At some archaeological sites such as Abri Pataud in France, 95-99% of the butchered bones come from reindeer. If this intense hunting did not drive the red deer or reindeer to extinction, is it reasonable to think it killed off the giant deer (Megaloceros) or woolly rhino (Coelodonta) for which there is little or no evidence of kills?

Americas

	Only 38 mammoths in the Americas are known definitely to have been killed by people.

Little evidence of hunting

Unequivocal evidence of the hunting of extinct megafauna is actually quite rare. Only 38 mammoths in the Americas are known definitely to have been killed by people - the skeletons of these animals having been found all across the USA and Canada.

This is very poor compared to the European evidence for hunting bison or reindeer, where remains of many animals can often be found on a single site

Next - In balance with nature in Australia and New Zealand