Ideas on Evolution - Page 2

mopc · #31 (**permalink**) 17-February-2005, 03:27 PM

Quote:

Originally Posted by lti

when breeding, each parent gives half their number of chromosomes. in a person that is 22, so the resulting offspring has 44 chromosomes (the same number as each parent).

In the case of a mule. Donkeys and horses have different numbers of chromosomes. a mule ends up with an odd number of chromosomes and as such is infertile because it cant evenly split his chromosomes for reproduction.

basiccally the main definition of whether two things are of a different species is whether they can interbreed. Horses and donkeys, however, can interbreed despite being of different species. creationists point out that this is evidence of them having 'evolved' from an original horse-like creature. No new information was gained in this process. it is the same as those birds u mentioned. Note: there is lots of examples of different species that can interbreed - lions and tigers, dolphins and whales. etc.

What about two different species which still look similar, similar sizes, and same number of chromossomes??? Are there any? What would happen???

Blob · #32 (**permalink**) 19-October-2006, 11:39 PM

Fish developed features characteristic of land animals much earlier than once thought, say researchers.
Dr John Long of Museum Victoria and colleagues base their conclusions on an uncrushed 380 million-year-old fish fossil found in Western Australia.

"The specimen is the most perfect complete three-dimensional fish of its kind ever discovered in the whole world" - Dr John Long , who reports the team's findings online today in the journal Nature.

"It looks like it died yesterday. You can still open and close the mouth."

Long says the preserved remains of a Gogonasus fish from the Devonian period (395-345 million years before present) were found last year in the remote Kimberley area at the Gogo fossil site, once an 'ancient barrier reef' teeming with fish.

Read more

http://www.ahc.gov.au/publications/geofossil/gogo.html

Latitude: 18°16'51.61"S Longitude: 125°35'57.05"E

The site is situated 100 km SE of the popular backpacking and conservation centre of Fitzroy Crossing within the Geikie Gorge National Park.

sarongsong · #33 (**permalink**) 20-October-2006, 08:02 AM

Quote:

Originally Posted by Nicolas

I only want to add that science tries to understand the mechanisms of the universe now and in the past, including how it came to be. But science doesn't look at why it came to be...

Coming soon:

Quote:

October 19, 2006
Physicist Stephen Hawking...is penning a new work. “The Grand Design” will examine how and why the universe was created. Publication date: fall 2008.
San Diego Union-Tribune

LayMan · #34 (**permalink**) 20-October-2006, 08:20 AM

"Physicist Stephen Hawking...is penning a new work. “The Grand Design” will examine how and why the universe was created. Publication date: fall 2008."

Rats, he's gonna beat me to it...

mugaliens · #35 (**permalink**) 20-October-2006, 06:10 PM

I know a guy who has webbed fingers and toes, proving that he at least carries some genetic material (perhaps we call do) that was carried over from a distant and possibly aquatic past.

What I'd like to know is why some people have large noses and some have small ones. Was there an environmental advantage, or was it due to what was considered beautiful or handsome over a long period of time?

Sock puppet · #36 (**permalink**) 19-February-2007, 11:57 AM

Quote:

Originally Posted by mugaliens

I know a guy who has webbed fingers and toes, proving that he at least carries some genetic material (perhaps we call do) that was carried over from a distant and possibly aquatic past.

What I'd like to know is why some people have large noses and some have small ones. Was there an environmental advantage, or was it due to what was considered beautiful or handsome over a long period of time?

When humans reached northern Europe, their ancestors had dark skin and large noses- and so did they. In African conditions, these are advantageous because they protect you from skin cancer and sunburn, and allow you to breathe properly (enough airflow through your nose) when you exert yourself. However, in northern Europe, too much skin pigment is bad, because it prevents you (among other things) from producing vitamin D. Similarly, a large nose with a wide opening lets you cool too fast.

When you're in northern Europe, dark skin is a disadvantage, but the big nose- well, that's a bit of a mixed bag: it still confers the same bonus as before, but also has a downside now. so you get a mixed selection pressure, which tends to produce a range of values (in this case, nose sizes).

Sorry if this is a little confused, I just sort of vomited my thought out onto the keyboard...

Disinfo Agent · #37 (**permalink**) 19-February-2007, 08:35 PM

Quote:

Originally Posted by Sock puppet

When humans reached northern Europe, their ancestors had dark skin and large noses- and so did they.

In African conditions, these are advantageous because they protect you from skin cancer and sunburn, and allow you to breathe properly (enough airflow through your nose) when you exert yourself. However, in northern Europe, too much skin pigment is bad, because it prevents you (among other things) from producing vitamin D. Similarly, a large nose with a wide opening lets you cool too fast.

Wide nostrils can be found in all sorts of different populations around the world -- in and out of Africa.

Sock puppet · #38 (**permalink**) 20-February-2007, 09:36 AM

Sorry, that was a rather poor attempt by me. To clarify, that was an illustration of just two of the selection pressures at work on nostril sizes. And it didn't even occur to me that nostril size and nose size may not be correlated.

Disinfo Agent · #39 (**permalink**) 20-February-2007, 03:45 PM

Well, I was actually thinking of either of the two versus skin tone, though the way I phrased my post was probably confusing.

Quote:

For example, skin color varies largely from light in the temperate areas in the north to dark in the tropical areas in the south; its intensity is not related to nose shape or hair texture.

source

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