How old is mankind? The question has to be understood in the
context of evolution. This is because humanity evolved from earlier types of
human-like ancestor species called hominins and we probably know more about
these peoples generally than we do of the very earliest Homo sapiens. The
reason being that fossil skeletal evidence is very rare to start with, only by unusual
chance conditions will a skeleton ever be preserved and fossilise, and to find
the earliest populations of Homo sapiens in a fossilized state will be
extremely unlikely but who can foretell what might be found in the future?
However rare they are to find in the field, there is
nevertheless a vast collection of fossil human remains (JW org insists there
are very few!) and also there is abundant evidence for their ancient presence by stone tools
preserved in caves and settlement sites all over Africa.
One of the best methods of preservation of human bones has
been to find individuals who had the misfortune to suffocate and die in a rain of volcanic
ash during an eruption. This chance happening has taken place numerous times in
the Great Rift Valley in East Africa which is known as the cradle of mankind. Here,
at the pace of a lame snail, the crust of planet Earth has been unzipping itself
for aeons creating these murderous volcanic events and then revealing its
actions millennia later as the giant cracks open up. In doing so, this tectonic
plate activity yields a number of fortuitous gifts to palaeontology in Kenya and Tanzania.
The first is that the ash from volcanic eruptions at a
certain distance beyond the pyroclastic flow can preserve in stone a snapshot as it were of everything
which was present on the landscape; footprints, animal tracks, men and beasts. The animal assemblage found in these deposits is important for
dating hominins. For example the evolution of members of the pig family
(suids) is well documented in the Great Rift Valley and the dates for each
species is known as are many other evolutionary lineages of African fauna. A
system of relative dating exists,
known from the layers of volcanic sediments with earlier animal and human species at the lower layers superimposed by later
species progressively revealed in the ascending strata formed mainly from volcanic
events. Not only can the stratum containing the hominin
and animals be ordered from relative dating (evolutionary sequences) but the matrix material can be
radiometrically dated (see Cofty’s excellent recommended reading on the subject by Dr R Wiens).
On top of that there is another dating method to corroborate the radiometric
and that is palaeomagnetism which works very well in airborne volcanic
deposits. This is based on the fact that Earth over geological time, for no
known reason, reverses its magnetic polarity, the north magnetic pole becomes
the south. There are minor reversals within the major reversals which can
pinpoint events in time to the dating expert and palaeontologist. It works by
the polarity of molecules of sedimentary material containing traces of iron
aligning to the prevailing polarity on deposition. By cross referencing all of
these dating disciplines against the backdrop of known prehistoric climate epochs;
The small brained short bipedal hominin called Handy Man (thinks:
Fats Domino) alias Homo habilis is
considered the first of the genus Homo whose debut was made about 2.5 million
years ago and died out around 1.4 million years back. There have been many Homo
species following Handy man including the important forerunner of our species Homo erectus who arrived around 1.9 million years ago.
As scientific evidence emerges there has been a continuous
pushing back the date for the earliest Homo sapiens and this year 2018, the
evidence looks now that our species has been around nearly 300,000 years.
Twenty years ago the fossil evidence was only for 150,000 years, twelve years ago it was 195,000 so the field of
scientific endeavour is active in this territory.
Or did God make man in 4004 BC as Archbishop Ussher decided
after calculating events in the Bible?