A Question of Evolution

Caveat: Since this is an question of exploring evolution, it is understood by all potential posters that anyone posting more than once on this thread will be considered as conceding that Biological Evolution does occur, without conceding the right to dispute any of the mechanisms therein.
A post shall constitute agreement.


Question: How do we account for the fact that Homo Sapient females are the only female mammals that are fertile more than once every 180 days?

I don’t have an answer, and I don’t know of anyone who does. Or any research into the matter.

But, taking what we know, it should be possible to deduce a possible answer.

Any ideas for a starting poiint?

 

We are talking about rhythm. Perhaps solar rhythm. we congregate at nesting season. Seasonal rhythm, we congregate to take advantage of seasonal changes, availability. Lunar rhythm, any where any time.

 

That's too much Evolution in too short a period of time to account for development of what is essentially a unique genetic disposition without radical environmental stimuli.

Consider:

the "seasons" have flucuated radically over the past 2 1/2 millon years.
And, assuming you know about Gravatic Title Friction (physics-- always physics!),
the lunar orbit has expanded considerably and the Earth's rotation slowed a meaningful amount in that time. Nethier was static enough for a long enough period of time to cause what may, in accordence with theory and observation, be considered a Cataclysmic Adjustment.

And in any case, Why would such rhythms affect only Human females?

 

Actually the rhythm has been established as a relatively unchanged constant for the duration. Climatic changes are frequent. The rhythms are of planetary motion, recurring lines of convergence, getting the parties together at the right place and time. Far ranging species would need a breeding ground and time to get there, birds. Cold blooded species need maximum solar radiation, reptiles. Time to gestate before conditions change, amphibians. Migratory species follow the seasons. Sedentary species wait for the seasons. Humans are the only ones who do it all. Humans are the only to occupy every eco-zone.

 

The climate has been far from stable over the last 2.5 million years. How many ice ages does that include, if nothing else?

Also, Humans had evolved to there present state, menstrual-cycle wise, before they spread far from their ancestral home. (Africa? Asia? Is it possible to really know?)

Let's refine the question: What Evolutionary Mechanism affected human females and no other mamalian females? Climate change alone isn't enough.
We can argue that Human's are unique in their intelligence, but the complexity of the Human brain may explain that. However, to my knowledge, the human reproductive system is not especially unique among Apes, except, I suppose, in gestation time.

is it possible that there's a tie between a 28 day menstrual cycle and 9 months gestation period?

 

If we sharpen our spears before we throw them we don't have to keep retrieving them before they stick.
Climatic changes are frequent. The rhythms are of planetary motion, recurring lines of convergence, getting the parties together at the right place and time. Lunar cycle means get together any time, any place, not dependent on seasonal or solar cues. Humans may inhabit the seashore, but may also inhabit the forest. They needn't travel far, they can inhabit every eco-zone of a mountainside. Certainly there is a tie between the 28 day menstrual cycle and 9 month gestation, the egg gets fertilized. Other than that I haven't come up with any, you? I don't think there is a mechanism that affects one thing and not another. I do not detect any discrete systems anywhere.

 

I don't think the abiotic environment was the main driving force behind changes in human female fertility and gestation . It probably has more to do with sexual selection and intra-sexual competition. I do not know enough at this time to give a specific answer but I do know that evolutionary psychologists study this type of phenomena and I will try to find some relevant studies to post here at a later date.

 

We're not looking for definitive answers here, we are developing theory so you are off the hook on that score, however data would be very useful. In the mean time we can check our postulates for integrity. Reality is no more real in one instance than another, no discrete systems. We have a choice of offering one measure or another, but that measure must apply to all things.

 

Upon consideration, it seems to me the obvious logical answer is a single dominant mutation. A possibility--

But it pushes the bounds of reason to believe a single mutated gene is responsible, and, if so, that it caused a one generational change in the human menstraul cycle alone. A virtual Eve from which we are all descended? It's possible--

But I would feel a lot better if there were evidence of either an at-least-somewhat-gradual-change or that humans were subject to some enviromental stimuli that singled them out among the apes.

The sad part is that all this makes a really good argument for UFO's and Gods.

 

Perhaps it lies in the nature of human activity. Not having to operate in a solar cycle frees the day for food collection, increasing the steady supply of nutrition. Many species cease to eat for extended periods in the solar cycle. This in turn feeds the night time wondering mind to refine the science of nurture. It really only approaches UFO or God if you confuse the amazing with the super natural. The environmental stimulus is the ability to peer into the night time heavens on the open plain. Both our beliefs and our present technology emerged from the night time sky. The ability to predict the seasons, computational thinking, produced simply from observing light and shadow. All of our discoveries have seemed amazing at one time or another.

 

You've got to admit, it borders the line of sheer chance that the difference exist at all.
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So here's more questions:

(I recently read this on the TIME site via CNN)

A large group of Foxes was bred for 22 generations. They were selected by a single criteria-- the first time a researcher walked up to the cage, the foxes that approached of their own accord were taken out and bred. 22 generations later, they have domesticated foxes.
Of course the study was far deeper than this, but it still begs a question:

Does that difference show up genetically?
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A Dog and a wolf are very, very similar, and indeed, can freely interbreed. But the dog and the wolf itself, the animal's being (for lack of a better word) is worlds apart. Does that show genetically?

And what about dogs themselves?
There's one hell of a physical difference between a german sheperad and an english bull dog, but if I'm not mistaken they both share Rotwieler's in their primary genetic lines. And they can interbreed.

At what point will evolution set in and speciation occur? Is it, perhaps along with the question of menstration cycles, only explainable by the occurance of a longshot of a chance mutation? Cataclysmic Adjustment?

 

I'm very with you here and have wondered about it this way. Why would a waters edge species not simply ebb and flow with the waters edge? Why even venture into the alien environment? When I observe animals, which I've spent a lot of time doing, I've noticed that individuals exhibit individual preferences and groups entertain common preferences. Individuals split off from groups and thus form new groups transmitting that individuals preferences as the preferential model for the new group. It appears to take a new idea, a new conception. What you might wonder, at what moment initial volition becomes self aware. I've noticed that a paramecium acts a lot like a dog.

 

This brings us to the Moon. There are, and have been even more so in the past, some pretty big ocean tides on Earth. Enough to impel the transition from water to land-- but again, a Cataclymic Adjustment is nessacary.
But without the extensie tidal pools and transitional shoreline caused by the moon the chances of the needed mutation occcuring at all, ever, would be ALOT smaller.
And if this reasoning is correct, what are the chances of an Earth-Moon type system Evolving? How many known moons circle the Solar planets?
it gives me pause-- maybe we are the only intelligence producing planet in the Galaxy.
A pretty dismal prospect.

 

Have you ever read Dune?

There must be something to the concept of genetic memory.
Muscle memory is Real; reflexes can be conciously created--
Perhaps Life operates on some kind of bio-molecular feedback system, just as it operates on the gross feedback of Emotional and Physical responses. Makes sense, really.

Kind of shoots the concept of Free Will in the foot, though.

 

I do not think that various breeds of dogs achieving the status of distinct species would require single cataclysmic change. As long as the breeding populations remain isolated the accumulation of minor changes might very well lead to speciation. But then again they will be capable of breeding to produce fertile offspring until an incompatible change occurs in gamete production, so it may require an important chance mutation after all. However I think it is appropriate to claim in the case of distinct breeds of dogs that the process of speciation has already begun and that each breed is, to use Darwin's term, an incipient species. A sort of evolutionary work in progress. The interesting thing about the study with the fox breed for domestic qualities is that consistent changes occurred in the shape of the ears and tails of each successive generation of those fox selected for breeding despite that fact that they were not selected on the basis of the shape of the ears or tails. An interesting correlation of growth indeed.

 

My reasoning is that the intelligent producing aspect is inherent of initial volition, Big Bang = Big Effect. From this reasoning, "intelligence", is no where absent. We confuse intelligence, which is a collection of information, with awareness.
What are the chances of an earth moon system evolving? Do the the fact that such a system can be shown to exist, I would say that it is not a matter of chance.
The awareness of life is not a sliding scale. It has a single parameter whose
expression ranges in intensity from the instinct for self preservation to gratitude. The wall of a cell is equal in effect to the instinct for self preservation.

 

Now THAT's interesting. Was the difference an artifact of the selection, or a pre-exisiting correlation?

As for speciation, where do we draw the line? Are Tigers and Lion an single species. They can breed, but they're not particularly inter-fertile.
And of course horses and donkeys, whom appear to be about to fall of the brink, so to speak.

Here's a thought:

Maybe it IS intelligent design, except that the intelligence is the organism's inherent ability to respond to stimuli and the design is on going, i.e., the response itself.

 

I agree. And thus I question the concept of "free will".

As to the earth moon system, we really have no answer, because we lack the mathematical concepts needed to figure it out, but it seems an unlikely occurrance from what is understood.

My instinct tells me that the Universe is crawling with Life, but intelligence (especially intelligence that doesn't eventually devise it's own end) is, perhaps, rare.

 

removed by me.

 

I was just considering posting on free will.
Humanity by and large has thus far managed only to posit a concept of free will. On very rare occasions is such a thing actually demonstrated. This is because early on in our lives we make a choice to abandon the concept of free will for the sake of upholding tradition. Tradition means to trade away or betray. In this state, we have the experience of the contested will, we appear to be in a competition with a hostile will.

I have read Dune. I have actually read relatively very few books, but I have concentrated on the cream of every genre I have investigated. By and large I have no more need for books and my investigations suffice. There was a debate in this house, posited be me, of whether my written contributions were at all necessary? So often do I find light in a consideration, only to discover that it already existed in another book.