lpetrich

The study of developmental genetics and evolutionary developmental biology ("evo-devo") has helped revive the notion of evolution by jumps ("saltation" and other fancy words).

It has usually been rejected for several reasons:

* Small mutations can be cumulative

* Large mutations are usually bad

* Small mutations are often much better-behaved

* This seems too much like a rabbits-out-of-hats hypothesis that can explain anything

However, developmental genetics has progressed enough to be able to chip away at the rabbits-out-of-hats aspect of such hypotheses. Consider the discovery of Hox genes, important for front-to-rear patterning. With numerous other such development-control genes now known to exist.

OrderedChaos

I am not to well informed on the other ones, but I know about cotton enough to comment on. There are four basic varieties of domesticated cotton, two of them old world and two of them new world. The two Old World species (G. arboreum and G. herbaceum) are each diploid, while the New World species (G. hirsutum and G. barbadenese) are both tetraploids. What is interesting about the tetraploidy of the New World species is that they are allopatric, which means that their genetic make up is the combination of the genomes of two distinct species (2n x2). What is even more odd is that they consist of the contributions comes from an Old World species (G. herbaceum) while the other contribution comes from a New World species (most likely G. raimondii) (Smith 1995). There are two hypotheses about how such an odd hybridization occurred. The first states that the introgression happened recently and as a result of humanity who transported G. herbaceum across the Pacific Ocean to the Americas. The problem with this idea is that for this to be true, one would expect feral varieties of G. herbaceum to be found in the Americas, when none are (Smith 1995). The other hypothesis is that the hybridization happened long ago, without human intervention. In this hypothesis, the combination had to have happened a long time ago when there was a connection between the two landmasses, either by a trans-Pacific land brides to the Polynesian islands, or before South America and Africa separated into two distinct contents. Cytological and molecular DNA testing suggest that the hybridization occurred about 1 million years ago, long after any connection with the Old and New worlds (Smith 1995). An interesting side note is that tetraploid cottons are native to areas in close proximity to seashores, suggesting that G. herbaceum seeds floated across the pacific ocean where they came in contact with the native G. raimondii. This might have been difficult because the time it would take to travel such a vast difference is longer then cottonseeds are able to survive in salt water. The true origin of this remarkable hybridization event still remains a mystery today.

So first of all the genome of cotton (new world domesticates at least) is not four times larger than its wild relatives, but simply two. Secondly the molecular evidence is suggesting that this event happend a million years ago, long before its domestication by man.

Smith, C. Wayne. Crop Production: Evolution, History, and Technology. John Wiley &
Sons, Inc., New York. 1995.

Albert Cipriani

Thanks All,
I read all the links. Excellent information. Especially UCD Lectures -- Sincerely, Albert the Traditional Catholic

MrDarwin

I'm afraid I don't have time to reply to this as in-depth as I'd like, but I'd like to point out a few things:

1. Regarding new crops being "discovered", how do we define "crop"? Is it something I can go out an pick on a roadside? Is it something that farmers in one isolated village in the Andes are growing? There are many plants at various stages along the way to domestication; some of them are simply more widely known than others and some are virtually indistinguishable from their wild progenitors (e.g., pawpaws). But when it comes to major crops like potatoes, corn, wheat, etc. there simply isn't much impetus to develop something entirely new because the existing ones are already so good (as evidenced by the rapid globalization of crops like corn and potatoes after Europeans discovered the Americas). How would somebody improve upon corn, wheat, and potatoes as crops? Not by developing entirely new crops, but by breeding the ones we already have for higher yields, better pest and disease resistance, etc.

2. These things were edible in their original, wild forms--but were difficult to harvest, or were extremely fibrous, or had big inedible seeds, or had to be cooked to get rid of bitter compounds, etc. For example, wild bananas have fruits with lots of big, very hard seeds with just a little pulp around them. They're quite edible, and often quite tasty, but a nuisance to eat and hardly worth the bother unless there's nothing else available. Pretty much all wild grasses are edible, but some have bigger seeds than others, some have their grains encased in hard shells, and most generally shatter (meaning that the seed heads fall apart easily, making harvest difficult).

3. There wasn't necessarily any artificial breeding going on at all. Wild populations vary, and single mutations can make a big difference. Finding a single plant with a mutation for larger or sweeter fruit, larger seeds (when the seeds themselves are valuable), or seedlessness, would make that plant instantly more valuable to early farmers. Another example (and probably accounting for the origin of things like wheat and seedless bananas) is natural hybridization. Hybrids are often faster and larger growing, more disease resistant, and more productive. Likewise, polyploids are often larger, more robust, and more productive; by doubling the chromosome number of a sterile interspecific hybrid (which can be induced artificially, but also can happen spontaneously) you get in a single generation a new true-breeding "species" that is a better crop than either of its parents.

4. Finally, in most cases we don't have any good idea just when a particular crop was domesticated.

joedad

Albert,

Diamond helped me understand the Garden of Eden creation myth. As humans left Africa and entered ecosystems that had developed and evolved without human presence, humans, upon their arrival, would not be recognized as threats. The animals would appear "tame." And of course we see this evidenced in the Galapagos, with Dodos, and with grizzlies on Kamchatka, and in other places as well. And to my knowledge, we've still yet to domesticate any reptilian species, which nicely explains the snake/serpent imagery of the Biblical Eden.

Of course, and eventually, these ecosystems change. Humans become part of the scene like everything else. We're no longer special or as "powerful." Quite a natural progression really, no deities necessary.

joe

Albert Cipriani

Dear Joe,
Trouble is, the Garden of Eden was a vegetarian’s paradise, not one for animal husbandry. Adam and Eve could have cared less if the animals were afraid of them or not. Adam and Eve were into fruit. Their curse upon expulsion from the garden was that the earth would no longer effortlessly provide them with food. Animals had nothing to do with it.

We’re more special (boob implants, transgender operations) and more powerful than ever. Everything about our behavior screams that we’re not at all natural and do not fit into Nature’s scene.

It’s our sense of not belonging here, of never being able to go home again, first articulated by story of Adam and Eve’s expulsion from Paradise, that is the leitmotif of our human condition. Most great literature is but a variation upon this theme. My hope in a supernatural order is founded upon my despair of ever being at home in this natural order you guys seem so comfortable in. – Sincerely, Albert the Traditional Catholic

Godot

Albert,
the comments generated in the OP are legitimate ones to raise, and they have been done so quite well without any need for me to add my two cents worth here. The journal article I reference at the tail of my post is not entirely relevant to your questions, but it certainly touches upon them from a differing perspective.

I would like to draw your attention to the source material you referenced. Nexus is an alternative journal, home of those pseudosciences that are maligned by the mainstream. If the majority of issues resemble the one I have perused in the past, there is very little meritous content between covers(I'm being generous; it's all crap).

~~~~~~~~~~~~
The Genetically Modified Crop Debate in the Context of
Agricultural Evolution. Channapatna S. Prakash. Plant Physiology, May 2001, Vol. 126, pp. 8–15, www.plantphysiol.org © 2001 American Society of Plant Physiologists.

joedad

I don't know what you mean by natural order, unless you just mean the "universe," in which case I will only remind you that you are the universe, the natural order. I really don't see any difference between us. But we digress.

Albert Cipriani

Dear Joedad,
Ugh! Have you been listening to that horrible pop tune by committee: “We Are the World”? We are not the world. We are not the universe. Such expressions of verbal nonsense are designed to suspend thought. Only zombies can repeat such mantras with a straight face.

You’ve heard of the “new world order.” If the way the world is ordered and the world itself are identical, then it, too, is a meaningless compounding of words and the UN ought to be disbanded, along with national boundaries and time zones.

Fact is, the world is one thing and the way we order it is another. Likewise, you are one thing and the universe is another. Human nature is one thing and animal nature is another. To meld the identify of man with nature is to blur the identity of both.

Fact is, evolutionary processes -- based upon the principles of randomness, competition, and environmental fitness -- order Nature. Thus, the natural order is antithetical to the supernatural order which is based upon the contrary principles of absolutes, love, and sacrifice. Nature can’t help but be the beast she is. But we have a choice. Choose wisely.

The differences between your supernatural nature and your animal nature are as profound as they are multitudinous. Suffice it say that they can all be summed up in the fact that you need meaning and seek reality as much as ducks need water and migrate south for it. Do you doubt this?

If you think that you don’t need meaning, that you are a part of the natural order that only needs to seek pleasure and avoid pain, then why not press the pleasure bar for the rest of your life? An electrode attached to your brain can give you more pleasure than sex for as long as you live. Rats will continue to press the pleasure bar until they die of exhaustion and/or starvation. They prefer it to food and water and will endure lethal electrical shocks to obtain it.

So why not you? If the lab techs could hook you up to an intravenous and give you a life of unimaginable pleasure until death do you part, would you not accept? If not, why not? Could it have something to do with the meaninglessness of such a life offending your sense of reality?

If so, congratulations for not being a rat. Congratulations for ordering your life supernaturally instead of dissipating your life naturally. Congratulations for obeying your supernatural orders instead and disobeying the natural order. – Sincerely, Albert the Traditional Catholic

DrummerWench

A highly readable (at least I found it so) book on this topic is The Emergence of Agriculture by Bruce D. Smith, Scientific American Library.

http://www.amazon.com/exec/obidos/tg...glance&s=books

I don't recall whether it was Smith or Jared Diamond who commented that, essentially, what is possible to domesticate has probably already been domesticated.

DG