A question about the evolution of people and the very first modern human born

Spoonman75

Ok. I accept evolution as a scientific fact. I'm non religious and I'm not a troll. The reason why I'm saying this is that creationists lurk everywhere on the interwebs and I want to be honest from the start.

What I (a layman) understand from the theory of evolution is that at some point in history somewhere in Africa a creature who was not quiet a modern human gave birth to a baby who had a genetic mutation that was a modern human. So this is the first modern human. Isin't it logical to think that if this baby was a boy, that an equivalent girl with the exact same genetic makeup (ie modern human) must have been born around at the same time so they could procreate and produce the third in a line of modern humans, we'll say a boy. If this boy's (the first true human I mentioned above) partner didn't match the genetic criteria of a modern human then their progeny would have the wrong genetic makeup and therefore not a true modern human and the true human genetic makeup is diluted before it can begin to flourish and is lost.

At the same time an exact same set of circumstances must have occured so that an equivalent female was born. If there wasn't then the resulting progeny would also not be a modern human.

So now we have one modern human male and one modern human female and not blood related. They both procreate and have a girl we'll call "X". I'm calling her this so to avoid a somewhat convoluted situation.

The exact same circumstance in paragraph 2 above must have occured to create a non blood related male to procreate with. The two other options "X" has is to procreate with the only other modern male that she knows but this is her father!

What are the chances that this could have occured or am I missing something? A selection of modern human males and females must have evolved at the same time and procreated with their genetically identical non blood related females and males to produce the human race. Or did all modern humans originate from just 2 genetically modern humans and alot of incest? From what I understand if they mated with any of the not quiet human counterparts (their only logical choice of mate a protohuman male or female equivalent of the first humane male I mentioned above) then the modern human genetic makeup could not sustain itself (as in paragraph 2 genetically diluted and lost.)

What am I missing here? Am I completely misunderstanding evolution? Thinking about this question makes me think about all distinct species of animals, not just Homo Sapiens. How many (is there a statistical preferable number of?) non blood related genetically identifiable humans of both genders that is necessary at the very beginning of human evolution to give us the now world population of 7 billion people?

I've made this question really complicated (I hope it makes sense) but any answers would be appreciated.

Thanks.

beardedmaster

I don't know enough about human evolution to talk at any length at all about this, but to be honest I think it goes down to a smaller scale in cases like this. It's a bit of a blurry line when it comes to which is a new species and which isn't - but what is certain is that it's more the traits of an individual which are beneficial and are passed down.
Individuals with these traits produce more offspring which are viable (themselves successful), as these traits are beneficial to the survival and success in the environment. It's when individuals with such specific traits (caused by the difference of maybe even one codon in their DNA which would encode one amino acid differently) get so specific in their traits that they eventually cannot mate with other creatures with similar genetics and produce offspring which themselves can produce children... that is when speciation occurs. Donkeys and horses, for instance, are different species - but can mate and produce offspring - mules. But mules are all sterile and cannot produce offspring themselves. It's when the traits/genes because so specific due to their longevity because of their success in the environment.. that's when speciation eventually ends up happening. I think! By no means am I an expert on the subject.

darjeeling

I don't think there was ever any single defining change that meant our ancestors went from being 'non-human' to 'human' in a generation.

The process is more gradual than that, and involves a shift in the overall population over time, such that if you took a snapshot of people several hundred generations apart, you might begin to detect differences between the ancestors and their descendents.

That speciation takes time is seen from a 2006 study of human and chimp genomes, which concluded that the human and chimp lineages separated, then remerged perhaps a million years later as proto-humans and proto-chimps once again interbred, before finally splitting around 6.3 million years ago. Even today, chimps and humans are more closely related than some species known to be able to interbreed....

Edit:

I should add, too, that there's good evidence from comparing human, Neanderthal, and now 'Denisovan' genomes that modern humans interbred with these distant cousins, from whom they had initially separated perhaps 3-400,000 years before.

nozzferrahhtoo

This article here is also on the same subject. While the OP is about Humans, the article is about a creationist making the same mistake about elephants.

The error is indeed to think that an individual evolved and then led to the entire human race. Populations evolve over time, not individuals. A single mutation in a gene sequence does not preclude procreation with other humans without that mutation either which is another error the OP made.

I imagine having cleaned up those two errors the OP will find the rest of it will fall into place, but as ever just ask if there is anything more you need help with.

Spoonman75

nozzferrahhtoo wrote: »

This article here is also on the same subject. While the OP is about Humans, the article is about a creationist making the same mistake about elephants.

The error is indeed to think that an individual evolved and then led to the entire human race. Populations evolve over time, not individuals. A single mutation in a gene sequence does not preclude procreation with other humans without that mutation either which is another error the OP made.

I imagine having cleaned up those two errors the OP will find the rest of it will fall into place, but as ever just ask if there is anything more you need help with.

*Facepalm*

I was mulling over my question today at work and I realised this mistake.

Off the top of my head I'm going to give an example. Dog breeders choose artificially selected mutations to produce different breeds. So we have for example a labrador and an alsatian.

Now these two breeds are of the same species but genetically have alot more than one different mutation between them. Yet the labrador and the alsatian can still breed and produce fertile offsprings which are still the same species ie the're still dogs.

This is correct?

darjeeling

Spoonman75 wrote: »

*Facepalm*

I was mulling over my question today at work and I realised this mistake.

Off the top of my head I'm going to give an example. Dog breeders have artificially selected mutations to produce different breeds. So we have for example a labrador and an alsatian.

Now these two breeds are of the same species but genetically have alot more than one different mutation between them. Yet the labrador and the alsatian can still breed and produce fertile offsprings which are still the same species ie the're still dogs.

This is correct?

Yes, that's right.

This is why modern humans were still able to breed with Neanderthals to produce fertile offspring, despite the mutational differences between humans and Neanderthals.

Capt'n Midnight

Imagine a very long table at one end is a modern man, then beside him is his father, next his grandfather, and greatgrandfather and so on all the way back.

If everyone was seated a yard apart then the person a mile away could be a Neanderthal.

Everybody would be able to talk with the people near them , but as the distance got further away it would be more different with the changes in language. Same is true for genes.

There is (probably*) no one transition point where you can point to a change in species, in the same way you can't tell where language changed.



* I do like the theory that we are a prematurely born ape. ie. the hair / facial features / neuron development go further in apes.

nozzferrahhtoo

Spoonman75 wrote: »

This is correct?

Indeed, genetic diversity is said to be somewhat wider in dogs than humans. I heard once the comment that if humans were dogs we would likely all be the same breed as the diversity between us is not that wide.... despite superficial differences that tend to get people in a knot such as skin color.