Show one complete lineage in evolution

i. There is a mystery about the theory of horse evolution. It arises from the fact that the brain of little Hyracotherium was simple and smooth, as indicated by the smooth inner surface of the fossil skulls. The brain of true horse, Equus, has on its outer surface a complex pattern of folds and fissures.35 Cattle brains are quite similar and equally complex and have an almost identical pattern of fissures. Cattle and Hyracotherium supposedly evolved from a common ancestor which had a simpler pattern of fissures. Therefore, it must be assumed that parallel evolution by chance processes produced the same complex brain pattern possessed by both modern cattle and horses. Such a tale is difficult to swallow. Intelligent, purposeful creation provides a more believable explanation.

methinks you mean earliest or oldest common ancestor

but they come to virtually the same thing:

would not the oldest common ancestor of all living genetically modern humans also be a genetically modern human?

and the genetic age is not a bound but an indicator of a bound: the age is not absolute and depends on the mathematical model to be correct, which in turn depends on a steady rate of genetic change.

One question that has come to me in the last week, is that if the apparent age of the "genetic adam" is less than the apparant age of "genetic eve" -- would this not argue for more doubling up of genetic markers in the adam lineage than the eve lineage ... and would this not be more indicative of early behavior similar to bonobos (where females roam and join bands where males stay) versus chimpanzees (where males roam and join bands where females stay)?

but I am interested in the question of whether the different group gender behavior would show up as different "adam" and "eve" ages for the respective populations.

Y chromosome Adam and mitochondrial Eve show reasonably close concordance of age according to several studies documented hereJust a moment...Both coalesce around 100-200,000 years ago.