[horizon (OP)]

When and where was the original "adam and eve" of the early humans/apes?
Ive always thought of evolution as a gradual thing over millions of years, fine.
But someone pointed out to me the other day, there must have been the original "mum and dad" of us all i.e if we traced back everybody's mums, mums, mums, mums etc it must lead to the same original pair of apes or early primate.

[Don_1]

Your original thoughts were correct. There was no single pair of apes which could be said to have been the Adam & Eve of the human race. There were probably more than one species of human in the first instances, but these would each have consisted of a great number of individuals which gradually evolved in a different way to the 'mother' species. Each group would have adapted to the habitat they were living in, over a long period of time. For example, those which came out of the forrests on to the plains, would have benefited from the ability to stand on their hind legs, thus Homo Erectus evolved. But this was not a single individual. All those apes which migrated to the plains would have been in the same position. The females would have chosen to mate with the males best adapted to life on their hind legs, so those would become predominant in the species, while those least adapted would not be chosen as mates, and so the best adapted gene would be the one to be passed on.

This would have been repeated for all manner of traits over many generations.

[CliffordK]

Evolution was a slow progress.  It may be difficult to discern the "first human" as there would have been a slow progression from early hominids about 5 million years ago to early homo sapiens about 200,000 years ago, to modern man.  And, even before that, it may be difficult to discern the first hominid vs primate.

However, when changes happened, they likely happened with small jumps.  And, most of the changes would have first occurred in a single family, or tribe, then spread to others.

In Genetics, mitochondria are passed only through the maternal lineage.  Men, of course, have them, but receive it from their mother, and don't pass it on.  Y chromosomes are passed through the paternal lineage. 

So, there is a concept of "Mitochondrial Eve" & "Y Chromosome Adam", from which all modern Humans have descended.  And, all modern humans have essentially copies of copies of that first mitochondrial genome carried by Eve, and all modern men have copies of copies of that first Y Chromosome carried by Adam.

Oddly enough, they don't occur at the same time.

Mitochondrial Eve lived about 200,000 years ago in Southern Africa.  Y-Chromosome Adam also likely was from Africa, but sometime around 60,000 to 142,000 years ago.  The discrepancy in time is likely due to a higher percentage of women giving birth than men fathering children.  Perhaps spreading of lineages through conquest, and capturing the women in other tribes.

There are also some hypotheses that there were a few times of extreme hardship for homo sapiens, and that they nearly all died out leaving only a few remaining individuals.  The resulting bottleneck helped limit the gene diversity.

There are also hypotheses that looking at only the Mitochondria and Y-Chromosomes fail to show the complexity of inheritance patterns.  For example, there is some data to indicate that long after the origin of the Homo Sapien species, there was actually some interbreeding with the more ancient Neanderthal race.  It is relatively easy to generate an inheritance pattern in which Homo Sapiens and Neanderthals interbreed, but after a few generations, only the Homo Sapien Mitochondria and Y-Chromosomes remain, but also some Neanderthal genes would still be retained in other chromosomes.

[horizon (OP)]

maybe adam and eve were 2 fish or 2 amoebas!

[Don_1]

Just to be a FOG, you don't need two Amoebas to reproduce, one is quite sufficient.