Evolution Question

LtCmd.Lore

I have a scientific question that has to do with evolution that I've ment to ask, due to the recent AWAKE:

If two dwarfs mate and have a child, will the child be a dwarf? What about two people with six fingers on each hand? Couldn't this theoreticaly bring about a race dwarfs or people with 24 digits? And then of course that race would have there own types of mutations, causing the human race to slowly change, or branch off!

The AWAKE made this sound impossible, and I want to make sure I'm right before I bring it up with someone...

I could have some fun thinking up cool mutations.

lovelylil

Ltc,

not sure I understand what you are asking. But here goes:

About the dwarfs, they will not neccesarily have dwarfs for children. I was watching a tv program recently about a couple of dwarfs who married and had three children. Two of them were normal and only one was a dwarf. A geneticist can give you the probability of having a dwarf child if both parents are dwarfs.

About the fingers - many people born with birth defects have normal children. There is a genetic condition where children are born with only two large digits on each hand and is known as the lobster claw syndrome. If a parent has the gene, it is usually passed on to the child. Again you need to see a specialist in this area.

What exactly is the point made in the Awake ? Lilly

Leolaia

These are not mutations...these are all within the range of genetic variation that already exists in the human species. Every so many births there will be a six-fingered child and every so many births there will be a child that will grow up at the low end of the height scale. None of these confer any particular reproductive advantage, especially among humans (in which cultural factors matter more than physical adaptations to environmental factors, and culturally people tend not to prefer mates that have six fingers or are very short), so their incidence remains very low. But if you look at another trait, such as sickle-cell morphology of red blood cells, then this does confer a selective advantage to people living in different environmental situations. Sickle-shaped cells result in anema which by itself is not a very good thing but which represents a selective advantage in places of the world where malaria is prevalent. Why? Because the parasite transmitted from the mosquito cannot effectively attack cells that are sickle-shaped, which thus prevent an infection.

But having an odd trait that gives selective advantage does not mean that that those that have the trait will "evolve into their own species". That requires a reproductive barrier, such that what was previously a single interbreeding population becomes split into two gene pools that no longer interbreed. The trait itself could pose a barrier to reproduction (perhaps it is a sexual turn-off, for instance), but the barrier could be due to geographical isolation or other factors. When the two gene pools are isolated over an extended period of time, then they can drift in their own directions, such that traits that might occur 1 in a million births in the original population might occur in 1 in a 100 in one population and not in the other. A trait would become more common for one isolated population because it is advantageous to it in a way it is not in the other population. These distinct populations that do not interbreed would then be distinct species with different morphologies.

peacefulpete

The odds of a child born of parents who are both dwarfs being dwarf is 75%. If one parent is not dwarf then the odds are 50%. Now this particular gentic anomoly is rather radical and has some serious additional health risks but hypothetically if the dwarfs were isolated or only dwarves survive some disaster, yes we would soon have a whole society of dwarves with tall-ies being a minority. Add some selection pressure, say lack of nutritious food, that would favor someone of diminutive size and the recesive tall gene would likely become a disadvantage being selected out. This is observed many times among other species (eg. dwarf mammoths and rhinos on islands) and seems to have happened at least once with hominids in Indonesia. IOW if only dwarfs survived the next astroid its possible that at least for a time the human race would remain dwarfs.

peacefulpete

I do have to disagree with you leolaia about Dwafism being simply low stature. It is a genetic anomoly caused by mutation, in some rare cases a newly arising mutation in others an inherited one.

peacefulpete

Here's a recent stories of how mice are triple normal size on this island and have adaptive behavior eating albatross chicks alive. Not technically on subject but intersting.

‘Monster mice’ are eating island's seabirds - Environment - MSNBC.com

Leolaia

PP...In rare cases, yes (for that is how such variability arises in the first place), but often an already-existing dwarfism gene that is inherited. Also I didn't mean to imply that there isn't a dwarfism gene in referring to "the low end of the height scale," no less than a gene involved in gigantism on the "high end".

Evolution Question

Share this