Why do people get so personal about defending evolution?

[frob2900]

Their ranges do not overlap in the wild.

Well, they overlap very little:

The Gir National Forest in India is the only place in the world where tiger and lion ranges overlap, fueling speculation that wild ligers roamed the area hundreds of years ago.

And still the article comments this:

Lion-tiger mating occurs in captivity. But it does not happen in the wild, probably for the same reason humans do not breed with gorillas or chimps.

 

[brennan]

See my above edit. The guy in that article was wrong. Lions and Tigers do not currently mate in the wild because they do not meet in the wild.

 

[frob2900]

See my above edit. The guy in that article was wrong. Lions and Tigers do not currently mate in the wild because they do not meet in the wild.

Yeah, ok, it's very possible the article is wrong. But still, it is rather obvious to me that whether or not species mate depends on much more than geographical overlap.

 

[brennan]

Normally you'd be right - the behavioural cues aren't right between most different species. But here we're talking about species that are barely different and that demonstrably can and do mate if the situation is right.

Spoiler :

And let's not talk about some of the wilder behaviour of humans. Or dolphins.

 

[frob2900]

Normally you'd be right - the behavioural cues aren't right between most different species. But here we're talking about species that are barely different and that demonstrably can and do mate if the situation is right.

Spoiler :

And let's not talk about some of the wilder behaviour of humans. Or dolphins.

Interesting. However, from an evolutionary standpoint it would make sense for males to mate with similar species despite behavioural cues. So why do males care?

For females it's another story. They have to carry the offspring for a long time, and if the genetics are incompatible, all that energy is wasted.

So I can understand a female of a species trying to use behavioural+pheromone/receptor cues to try to determine the healthiness of the offspring with a potential mate, but for males it doesn't make sense.

 

[warpus]

SO are there any 'links' in evolution that could breed. (like cro-magnon and neandertal - could they?) If not, how could they evolve into the other. How could a species jump species? So far there is little to no evidence that neandertal and cro magnon could breed. And even under the assumption that they could you would end up with a sterile offspring. However, that is speculation at best at this point as is saying they definatly couldn't breed.

You are thinking in discrete terms. It's like thinking of a circle as something like this: (a discrete approximation)

then looking at an actual circle (or sphere) and asking where all the edges are.

Evolution is a continuous process. Species, as we define them, are a discrete human invention that helps us categorize life on this planet.

 

[Eran of Arcadia]

@brennan: So why don't humans and dolphins breed?

(Or humans and bonobos, which is almost reasonable. Except we split about 5-7 million years ago, so that probably is too long.)

 

[brennan]

In most species it's the male that is most promiscuous.

Notable exception:

Spoiler :

Male spiders (and some other bugs) don't often get the chance (shudder)

 

[brennan]

@brennan: So why don't humans and dolphins breed?

(Or humans and bonobos, which is almost reasonable. Except we split about 5-7 million years ago, so that probably is too long.)

Turn off your obscenity filter and look up 'beastiality'...

 

[Eran of Arcadia]

The obscenity filter on my computer, or in my head?

(I guess you are right about that though, although I think the motivations of the individuals involved are a little different.)

 

[frob2900]

In most species it's the male that is most promiscuous.

I mean inter-species promiscous. I think the intra-species bit is pretty clear

 

[bhsup]

It's rather disturbing, unless you live in Australia I guess, and I don't know how this was tested, but I distinctly recall reading once that human sperm can actually fertilize a sheep egg, but then it dies almost instantly.

 

[Gogf]

SO are there any 'links' in evolution that could breed.

Okay, first of all, get this "links" idea out of you head. Evolution is a slow, gradual change. There is no sudden, dramatic change from one species to another. It may appear that way from the fossil record, but that's because the fossil record is incomplete.

(like cro-magnon and neandertal - could they?)

It doesn't matter, unless we want to advance the theory that humans are some sort of crossbreed between cro-magnons and neanderthals.

If not, how could they evolve into the other.

Something does not need to be able to be able to breed with its evolutionary descendants. Put another way: something does not need to be the same species as what it evolved from.

How could a species jump species?

It couldn't. There is no "jumping." Change is species is extremely gradual.

So far there is little to no evidence that neandertal and cro magnon could breed. And even under the assumption that they could you would end up with a sterile offspring. However, that is speculation at best at this point as is saying they definatly couldn't breed.

All this means is that cro-magnons and neanderthals were different species. I'm sure you'll agree that one species can evolve into another.

 

[Gogf]

It's rather disturbing, unless you live in Australia I guess, and I don't know how this was tested, but I distinctly recall reading once that human sperm can actually fertilize a sheep egg, but then it dies almost instantly.

Plenty of difference species can reproduce with each other. For example, a mule is a crossbreed between a horse and a donkey. However, different species cannot produce fertile offspring.

 

[bhsup]

Not really comparable.

Horse and donkey: Same class, order, family, and genus.
Lion and tiger: Same class, order, family, and genus.
Human and sheep: Same class, but that's it. Beyond both being mammels, our family tree splits.

 

[Gogf]

Not really comparable.

Horse and donkey: Same class, order, family, and genus.
Lion and tiger: Same class, order, family, and genus.
Human and sheep: Same class, but that's it. Beyond both being mammels, our family tree splits.

Fair enough .

 

[mangxema]

Okay, first of all, get this "links" idea out of you head. Evolution is a slow, gradual change. There is no sudden, dramatic change from one species to another. It may appear that way from the fossil record, but that's because the fossil record is incomplete.
...
It couldn't. There is no "jumping." Change is species is extremely gradual.

King: Think of it this way. Presumably, you're an adult. At one point, you were a baby. Let's say you have pictures of yourself taken every year or so. So looking at the pictures, I might say that you were a baby, then all of the sudden you were a toddler, then all of a sudden you were a teenager, then all of the sudden... That is basically what you're saying.

Of course, that is dead wrong. Growth is a very slow and continuous process, with your body constantly changing slightly over many years. Age is really a man-made convention to help group similar beings together. Similarly, evolution is a very slow and continuous process, and species are man-made conventions.

 

[brennan]

Good analogy. I'll remember that.

 

[King Flevance]

Sorry, I had to run out and try to put a computer in the shop, but it looks like they are closed until Mon.

First off I want to clarify that I understand the idea behind the theory of evolution. But considering the facts I find personally the results inconclusive. It isn't the same as showing me pictures of a child growing at different ages. Because I see children growing all the time with my own eyes. I have neices, siblings etc. I do not see anything evolve in my own lifetime. About the closest thing to evolution I can see happening today is cancer.

Humans have been around for thousands of years and we haven't been able to find proof of 1 single gradual evolution of a creature. We have found proof that there are creatures that appear to have evolved from others possibly. But no real proof that one ever did. (I mean soley going off of the evidence at hand.) We can theorize about it, and yes it is a good theory. But it isn't proven to me yet. I will admit I don't research the topic much, because in the end I don't find it that important. I find it interesting and I like discussing it, but I am pretty much neutral on the whole thing. Evolution doesn't effect me in any way I can think of whether its true or not. So I gain nothing by just accepting it as absolute truth. I would close my mind on a certain chapter about life and I don't feel enough proof is out there yet to do so. I am not saying there never will be enough proof. But there just currently isn't yet to my knowledge.

Okay, first of all, get this "links" idea out of you head. Evolution is a slow, gradual change. There is no sudden, dramatic change from one species to another. It may appear that way from the fossil record, but that's because the fossil record is incomplete.

As Gogf put it, the fossil record is incomplete. It does appear that way through the fossil record to me. And that isn't enough proof. I may leave this life never being certain if evolution is fact or best guess. But that's fine by me. That is way down on my priority list.

 

[brennan]

I take it you are unaware of TalkOrigins?

Please browse the observed instances of speciation FAQ

Humans have been looking for speciation events for a geologically insignificant period of time. We are only likely to have observed them in species with rapid reproduction rates (which is of course what we find).