Irreplaceable Loss Extinction as the Loss of Information

Extinction means "to be lost" or "to go out of existence." Losses can be of many types. We usually think about extinction as the loss of something physical, but we can also think about it as the loss of information.

Species are physical entities, but they also carry information bound up in their genetic codes. We know that the genetic code of every species, as shaped by evolution, is unique at some level compared to that of every other species. Thus, when the last individual of a species dies, what also disappears are the unique aspects of its genetic endowment.

In this sense, all extinctions that have occurred in earth's history are the same: every one of them involved the loss of a packet of unique genetic information when the last individuals carrying that packet died.

Recently, scientists have been able to recover small pieces of mammoth DNA from well-preserved permafrost mummies and bones. As would be expected, their DNA differs somewhat from that of living elephants.

Woolly mammoths (Mammuthus primigenius) appeared in Asia about 2-3 million years ago. They evolved from the same ancestral group that gave rise to the living Asian and African elephants (Elephas maximus and Loxodonta africana). Woolly mammoths physically differed from living elephants in their size, ear shape, tusk dimensions, and, of course, their long hairy coats. These physical differences are indications that woolly mammoths differed genetically from other elephants.

Woolly mammoths lived in Eurasia and also in North America. North American populations disappeared at the end of the Pleistocene; those in Asia persisted somewhat longer (until about 4,000 years ago on Wrangel Island in the Siberian Arctic Sea). When the last individual died out, Mammuthus primigenius and its unique genetic endowment disappeared forever.