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

If there is so much debate around current views then what needs to be covered to make the correct statement?

Lipids?

DNA?

Well Bishadi, (welcome to h2g2), you can forget about the debate/dispute that seems to be very prominent in America concerning creationism vs Darwinism. If you are at all familiar with the original Hitchicker's Guide to the Galaxy, then you must be aware of the ultimate answer to the ultimate question:

What's the answer to: life, the universe, everything?

The answer of course being 42.

Regards, Lapis

thanks but i was looking for an answer not a debate. Just want to see how much I can learn from this group.

The core concept is descent with modifiction.

More animals are born than can survive to reproduce. New traits that are beneficial spread through a breeding population. Traits tht are harmful die out. Over time the popultion changes.

The process is gradual. Geology and dating methods from physics provide proof of the necessary timescale. Genetics (DNA) provides the necessary mechanism of heredity.

Noggin

Hmmm, depends on who you are trying to eplain it to. Are we talking a small school class of children, or a group of adults?

What is your current understanding of evolution?
If you have a reasonable grasp of the subject you'll naturally be able to select an explanation appropriate to your audience of the moment

Short definition: Evolution is characterized by a change in the frequency of alleles in a population over time

Long definition: Look here -- http://www.bbc.co.uk/education/darwin/

Or for a slightly simpler/shorter introduction -- http://www.mansfield.ohio-state.edu/~sabedon/biol1510.htm

Closer to home, <./>search</.> hootoo for a few relevant articles. A673319 is a good start.

Other than that, pretty much what Xanatic said.

"Evolution" is actually a bit of a misnomer; the word was absent from the first edition of "Origins". It implies some kind of directionality, but evolution simply describes *change* in living things over time. Evolutionary biology attempts to describe how this change happens.

I don't have time for a long post right now but I will in a few days or so.



Ste

How do you explain evolution? As Xanatic said, to who? The audience is everything. You'd explain evolution to a gaggle of squirmy primary school children and a room of professional scientists very differently indeed.

"Descent with modifiction" - trust Noggin to find the most concise description.

To elaborate - there are some basic things you need to get evolution going. Inheritance, variation, and natural selection. DNA is the hereditary molecule and traits are encoded in genes that are inherited as discrete units which leads to Mendelian inheritance. Genomes are highly dynamic things: Variation is key to evolution. Random genetic drift, mutation of DNA, selfish genetic elements, and genome duplication all contribute to stir up the hereditary material of populations. Natural selection subsequently acts upon this variation and adaptive genes/traits tend to increase in frequency in the population (positive, Darwinian selection), while deleterious genes/traits are kept rare (negative, purifying selection). Evolution is a remarkable self-optimising, self-adapting, self-maintaining system.

You can also look at evolution in a more intuitive sense. You are more similar to people who are related to you and vice versa. This principle holds from the organismal (morphological) to the molecular (DNA) level. From this you can build up phylogenetic trees of relatedness and eventually get a "tree of life". We share 50% of our genes with a banana. All life is related. It's just a matter of how much.

Is this the kind of thing you are looking for? Do you have any more specific questions because I really could just go on all night...


Ste