h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

'Now differences in chromosome number do not serve as reproductive barriers between all species. For example, lets look at some of the equine species ( horses and donkeys). Domesticated horses have 32 pairs of chromosomes and Donkeys have 31. Yet, they can produce offspring, mules, which have 31.5 pairs of chromosomes. One of the horse chromosomes goes unpaired. Wild mountain zebras have 16 pairs of chromosomes, while the last species of wild horse (Przewalski's Horse) has 33 pairs. However, all of these equine species can produce hybrid offspring. In all of these crosses but one, the offspring are sterile. It has long been argued that this sterility is due to the difference in chromosome number, but hybrids of the wild (33 pairs) and domesticated horse (32 pairs) are fertile, and have 32.5 pairs of chromosomes. So clearly, something more than just differences in chromosome number is contributing to the species interbreeding barrier.'

http://madsci.wustl.edu/posts/archives/may2001/989331026.Ev.r.html

Sorry, but it isn't so clear that there is a problem with humans and chimps.

"However, all of these equine species can produce hybrid offspring. In all of these crosses but one, the offspring are sterile."

It looks like someone found an exception to the rule. But the rule is that species with different chromosome numbers produce non-viable offspring, if at all.

Ste

Actually, the situation with equines is that two groups can produce viable offspring despite chromosome number differences: the case mentioned in that link I provided and this one: 'Donkeys have 62 chromosomes, while horses have 64.

A female mule, called a "molly," has estrus cycles and can carry a fetus, as has occasionally happened naturally but also through embryo transfer. The difficulty is in getting the molly pregnant in the first place.'

http://en.wikipedia.org/wiki/Mule

It is also worth considering the conversation associated with that wikipedia article:

'The article says all males are sterile. I question this. I've read that when male mules are almost always castrated, because if they aren't castrated they are very sexually agressive. I think this means that the fertility of male mules is never really tested.

The article says female hinnies are always sterile, but that almost all female mules are sterile. I question this as well. I've read that while mules are generally larger, there is no sure way to distinguish between adult mules and adult hinnies biochemically. But that one can distinguish them by putting them in a paddock that contains both horses and donkeys. It will go hang out with its mother's species.

I suspect that rather than almost all mules being sterile, all mules are almost all sterile. I suspect that the chromosome match between the hybrid's gamete and the full-blooded horse or donkey's gamete is always problematic, without regard to the sex of the hybrid and the full-blood. I suspect that what the article states -- that some rare female mules are fertile, and all the rest are sterile is incorrect. Rather that all mules have the same slim chance of generating a gamete that can join with a full-blooded parent's gamete to make a viable offspring, and that we would be seeing male hybrids making the occasional baby if they weren't always all sterilized. -- Geo Swan 03:08, July 11, 2005 (UTC)'

http://en.wikipedia.org/wiki/Talk:Mule



Yes, the rule is that species can't interbreed, but it is a human-made rule.

I tell you, Reality Television will prove the point with humans and chimps in our lifetime.

I'm not very convinced. It does seem like an exception still; that every now and again mules can breed. In a natural species such a fitness drop would be catastrophic.

Two (usually recently speciated) species can interbreed at a low level at the fringes of the population's range. These are known as "hybrid zones". Just because a small subset can breed, doesn't mean they're not two species. The boundaries are blurry, probably because (as you hint at) it is a human-defined thing and probably not all that correct.

I'm sure reality tv (lowercase letter, please ) will provide the impetus to test these human-chimp hybrid theories in the near future. I fully agree.



Ste

'it is a human-defined thing and probably not all that correct.'

I agree (as I should, since you are agreeing with me)

The sign of a good theory is that it is able to make verifiable predictions. Earier this year the 'Aquatic Ape theory' gained more credibility when a prediction was verified. Human babies are born, covered with 'vernix caseosa', a waxy substance covering the body. It is not found on any other land mammal but was predicted that aquatic mammals should have the same covering at birth. Verification of this came at the begining of this year.

alji

Now this is a news story we've all been waiting for!!




'Under a new law designed to protect minors, local police departments will now be required to inform residents any time a known Roman Catholic church moves into their neighborhood.

New Jersey State Senate debating Egan's Law The law also mandates that Catholic churches register with authorities, wear electronic monitoring devices, and be prohibited from moving to within a half-mile radius of a school. '

http://www.thiswaydown.org/sinners.html

>'Under a new law designed to protect minors, local police departments will now be required to inform residents any time a known Roman Catholic church moves into their neighborhood.

>New Jersey State Senate debating Egan's Law The law also mandates that Catholic churches register with authorities, wear electronic monitoring devices, and be prohibited from moving to within a half-mile radius of a school. '

>http://www.thiswaydown.org/sinners.html

az

Seems the Flying Spaghetti Monster has competition: The Invisible Pink Unicorn http://www.palmyra.demon.co.uk/humour/ipu.htm

I have seen the error of my ways. From this time forth, I will devote my life to the worship of her Pinkness.

The first "Imaginary religious war" is on the way methinks!

I can't resist; if you're worshipping Her Pinkness and you see a purple oyster you're very near the end. That said, it's Thursday and I never could get the hang of Thursdays.

YOU'LL FIND OTHER RELIGIONS EXPERIENCE THE SAME PROBLEM, HOWEVER THE EVOLUTION THEORY HAS BEEN REFUTED SEVERAL TIMES.

Firstly, UPPER CASE IS GENERALLY CONSIDERED TO BE SHOUTING, AND POSSIBLY EVEN A LITTLE RUDE.
If it is at all possible to use mixed-case, or lower case, many people would appreciate it.

Regarding refute:

Definition
1. To prove to be false or erroneous; overthrow by argument or proof.
2. To deny the accuracy or truth of.

I *guess* you're using it in the second sense of the word (ie disagreed with, not disproved). That's not exactly front-page news, since some people have disagreed with the idea from the start.

In the *first* sense of the word, what would be the point proving something false *several times*?

UNLIKE YOUR NAME, AND IT'S RUDE TO BE SAY WHEN NOT SPOKEN TO, AM MERELY POINTING OUT, NOT TO TAKE THE EVOLUTION THEORY TO HEART, PS I CAN WRITE HOW I WANT, LOOK AT WHAT IS BEING READ NOT HOW IT IS WROTE.

What is written is ungrammatical and pretty much --

Oh, never mind. Go ahead and blather on incomprehensibly.

And we have another one!

What's with Potholer's name? Isn't that just a British term for caving, or spelunking (or whatever the US word is)?

Would it really kill you to press the Caps Lock key off? It is actually quite hard to read what you are saying, and if you expect anyone to read a longer post, you'll have to write normally, cos no one will bother reading a long post if it's all in capitals.

Still my good fellow it is rather impolite to ignore local customs.

Here at hootoo that custom is to type lower case thusly. It really does make it easier to read.