Thanks again, Jeanie.

Old geologically or individually old?

If the former, then we know by comparing them with other fossils of the same ages (say dogs) that do not show the same kind of changes in skull size compared to body size.

If the later, then we know the ages of many fossils by the imprint of different stages of development that is left on the bones. We know that some are children and some are very old - for their species (almost 35 years old) - and some that are in between, just as we know that some are male and some are female from the bones.

We also have multiple samples of different species, so we can rule out the argument that the one in question was deformed or diseased.

Well, you do live in the south ... (joke).

What you see is the amazing amount of natural variation that can occur in a species, possibly augmented by (a) the thousands of ecologies that humans have adapted to and (b) the propensity of humans to adapt nature to themselves, and thus preserve traits that may not otherwise be beneficial.

Let me see if a graphic helps here:



Notice that each of the horizontal dark lines are populations of fossils, showing the variation in each population. Notice that each of the populations shown is intermediate between the one before (below) and the one after (above) with a high degree of overlap in the characteristics of each population.

Notice that Pelycodus ralstoni evolves into Pelycodus trigonodus which evolves into Pelycodus jarrovii by gradual change in the hereditary traits in the populations from generation to generation. These species classifications are fairly arbitrary, as they are just a way of saying that P. trigonodus is different from P. ralstoni, however then we have the non-arbitrary speciation event where P. jarrovii evolves into two separate populations, Notharctus nunienus and Notharctus venticolus.

You can see that there is overlap between P. jarrovii and the daughter population, N. nunienus and that N. nunienus evolved from P. jarrovii by gradual change in the hereditary traits in the populations from generation to generation.

You can also see that there is overlap between P. jarrovii and the daughter population, N. venticolus and that N. venticolus evolved from P. jarrovii by gradual change in the hereditary traits in the populations from generation to generation.

Finally, you can see that Notharctus nunienus and Notharctus venticolus diverge to a point where there is no overlap between their respective populations, and that they are no longer sharing genetic information, but evolving different hereditary traits in their respective populations (and if you read the article you will see that they diverge further in later (higher) layers, one forming a new genus).

So to answer your question, the evolution of Notharctus nunienus from Pelycodus jarrovii does not prevent the evolution of Notharctus venticolus from Pelycodus jarrovii. Yes, they are siblings, their offspring will be cousins, and their offspring will be second cousins, etc.

Is Notharctus nunienus more or less evolved than Notharctus venticolus? No: at any time at any place, any two organisms are equally evolved from their common ancestor.

Bacteria evolve faster than humans (because they have shorter generations): does this mean that they are "more evolved" than humans? The terms "more evolved" and "higher evolved" are meaningless in evolution, as evolution is only concerned if and when evolution occurs.

If you want to know if one species, or one variety of species is special (however you use the term) compared to others, then you will need to look at philosophy and religion.

I hope that helps. Show this to your husband and see if he still has a problem with apes living today.

Meanwhile, thanks for the opportunity to introduce another set of intermediate fossils that show an evolutionary transition from Pelycodus ralstoni to Notharctus nunienus and Notharctus venticolus, a transition that has hundreds of intermediate fossils at many different stages along the transition.

Are there gaps in this fossil record? Yes, however not enough to cause a problem, because there is still sufficient overlap to show the hereditary relationship between one population to the next. One can also predict that if new fossils are found in the right time and ecology to match those gaps that you will find more intermediate fossils.

Enjoy.