We want to find out about our ancestors and to collate
information from every source that we can. However, this
insatiable thirst for knowledge can lead us to adopt unreliable
sources of information. Unfortunately, we cannot dig up a
living, breathing ancestor, or use a time machine to study the
past directly.
All living organisms are ‘cousins’ that share a common
ancestor some time in the past. Each pair of contemporary
organisms is equally derived in terms of time from this
common ancestor (see Figure 1.4), yet the concept of a ‘living
fossil’ or a ‘contemporary ancestor’ is pervasive. This concept
insinuates itself implicitly or explicitly into all levels of the
tree of life, as illustrated by misguided statements such as
these:
The first living organisms were like bacteria.
The coelacanth is a ‘living fossil’ of the first four-limbed
vertebrate.
Humans evolved from chimpanzees.
Modern hunter–gatherers resemble humans before the advent
of agriculture.
The Basques are a Paleolithic relict population.
At the inter-specific level, this concept derives in part from
an anthropocentric view of nature: that humans have
transcended the rest of the natural world, and that we have
progressed beyond the bounds that limit other species (see
Sections 13.5–13.7). Potential dangers lie in the assumption
that in the absence of evidence about the common ancestor
of humans and any other species, the nonhuman species is a
closer approximation to this common ancestor.
A misconception of inevitable progress also dominates
popular thinking about diversity within humans. Ancient
populations are often assumed to be less like modern Western
societies and more like ‘less-developed’ indigenous peoples.
Yet it is well accepted within anthropology that ethnography
(the study of living peoples and cultures) can be a poor guide
to the past.
If there is any basis to this common misconception, it
must lie in some measurement of evolutionary derivation
other than time. In principle evolutionary derivation may be
measured in terms of: