Glossary

Blitzkrieg A specific form of the overkill hypothesis formulated by Paul Martin with respect to Pleistocene extinctions in the Americas. In blitzkrieg overkill, humans encounter faunas naive to human predation making them extremely susceptible to extinction by hunting. Rapid human population growth and geographic spread are fueled primarily by hunting of large game, and human colonization and faunal extinctions are complete within a millennium.

Hyperdisease A hypothesis developed by Ross MacPhee and Preston Marx to explain the extinction of Quaternary faunas. The hyperdisease hypothesis argues that many prehistoric ‘‘first-contact’’ animal extinctions are explained by the introduction of hyper-virulent and hyper-lethal diseases first introduced to animal populations by colonizing humans and/or their domesticates (e. g., domestic dogs).

Megafauna A term generally used to refer to the largest animals present within an ecosystem, most often used with respect to the array of large-bodied species which suffered extinction during the Quaternary. A strict definition refers to animal species weighing more than 44 kg (approx. 100lbs).

Overkill hypothesis The hypothesis that most animal extinctions of the Quaternary can be directly or indirectly attributed to predation by humans.

Sitzkrieg A hypothesis developed by Jared Diamond to explain the extinction of Quaternary faunas. The sitzkrieg hypothesis refers to slow, drawn-out extinction events caused by secondary human effects, such as deforestation, anthropogenic burning, and general habitat modification.

Humans and hominids lived side by side with the woolly mammoth, rhinoceros, cave bear, giant deer, and straight-tusked elephant for thousands of years. They even left painted depictions of some of these animals on cave walls (Figure 1). When humans first arrived in Australia some 50 000 years ago, the island continent was inhabited by a menagerie of marsupial mammalian, avian, and reptilian megafauna. Yet by comparison, the world’s large fauna of the modern era are much reduced in diversity and geographic extent. Surprisingly, though the extinctions of the Quaternary are the most recent ‘mass extinction’ of the fossil record, the issue of cause remains largely unresolved.

The idea that humans caused Late Pleistocene extinctions through over-hunting is known as the ‘overkill hypothesis’, but other explanations have been proposed. For example, some argue that Quaternary extinctions may have been caused by climate and ecological changes that have occurred during the last two million years. Others suggest that extinctions may have resulted from the introduction of novel and highly lethal pathogens by humans to populations of animals. Still other researchers have proposed multi-causal explanations that point to both human and natural causes. Of course, extinctions of all taxa in all places and times in the Quaternary need not have the same cause. Different factors may account for animal extinctions over time and space, and dauntingly any or all of these explanations could be correct when viewed at a global scale.