Hi William, As far as I understand it, most of the studies on past organisms are done at the genus level, not the species level, making accurate evaluations of species-life-spans exceedingly difficult. The fuzziness of where the line is drawn dividing where one species becomes another adds yet another level of difficulty.
The fossil record bias toward preserving remains of larger animals rather than smaller ones would also seem to impart a potentially heavy bias in estimating species-life-spans as well. Within the homo/Australopithecus lineage, *H. erectus*, has had the longest run so far, with most of the other branches of the family being relatively short-lived. I don't know of any agreement as to why this is. I've heard suggested that it's a product of poor fossil record, that it is a reflection of a period of rapid evolution with many different forms speciating rapidly, then dying off, and that it is an artifact of artificially creating different species categories. The article below indicates a mammal average species-lifespan within the time-frame you've mentioned, but that estimate may be subject to some of the biases I mentioned earlier. "Mammals are among the fastest-radiating groups, being characterized by a mean species lifespan of the order of 2.5 million years (Myr)1, <http://www.nature.com/nature/journal/v443/n7112/full/nature05163.html#B1>2<http://www.nature.com/nature/journal/v443/n7112/full/nature05163.html#B2>. The basis for this characteristic timescale of origination, extinction and turnover is not well understood." http://www.nature.com/nature/journal/v443/n7112/abs/nature05163.html Good luck with your search, I'd be very curious to learn what you discover. Neahga Leonard On Thu, Jul 19, 2012 at 10:37 AM, William Grove-Fanning < [email protected]> wrote: > To clarify: I > mean the the lifespan of the sub-species Homo sapiens sapiens, not the > life-span of its > individual members. I believe that for species of larger mammals, it is > around 1-2 > million years, but need to firm up and be able to cite any such number. > > Thanks Again, William > > > Date: Wed, 18 Jul 2012 10:16:39 -0500 > > From: [email protected] > > Subject: [ECOLOG-L] Lifespan of the Modern Human (Homo Sapiens Sapiens) > > To: [email protected] > > > > I am doing research for a paper that requires a fairly general answer > to what appears to be, at least on the face of it, a fairly simple > question. But I am having a heck of a time finding any sort of answer. > Here is the question: > > > > Has anyone estimated or tried to estimate the life span of the modern > human (homo sapiens sapiens)? > > > > The question, of course, gets muddied quickly with the possibility of > genetic manipulation and other self-directed evolutionary interventions; the > > creation of isolated human populations in space; and a global disaster > that wipes out all life on earth. But assuming a “base rate” of human (or > mammalian or large mammalian) speciation, how long is the modern human, as > a sub-species, expected to be around? Alternatively, what is the average > life span of members of the genus Homo (e.g., Homo sapiens, Neanderthals, > Homo erectus, etc.)? > > > > > > > > If someone could point me to a citable source, I would reallyappreciate > it. Thanks! William > > > > - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - > - - - - - > > William Grove-Fanning, Andrew W. Mellon Fellow > > Department of Philosophy, Environmental Studies Program, Trinity > University > > Secretary-elect, Newsletter Editor, & Website Manager, International > Society for Environmental Ethics > > > > >
