Somebody please explaind descent with modification to me

[laxboi33]

In the natural selection section of my biology book it says that several species originated from one species. Nature then selected who would survive and who would die out based on the strength of the species (the features that were most advantageous etc.) Here are my questions:

 

1. Where did all of the other species come from? Were they genetic mutations or were they modified? And if they were modified how were they modified?

 

2. My book also states that there was descent with modification. How did these modifications come about? Did the environment trigger these modifications?

 

3. Doesn't this whole theory of nature selecting the stronger species favor creationism over evolution? My knowledge on evolution is rudimentary, but from what my book is telling me, there was no such thing as evolution. Several species already existed and the strong survived.

 

 

can someone please explain this to me?

[Mr Skeptic]

Variation comes from mutations (fancy word for changes to the genes), which are occur in or are passed on to the offspring. This makes them different from the parent despite being mostly similar, and is the heart of descent with modification. It is a verified fact that mutations occur.

 

Natural Selection is a common sense process which is a logical necessity. It says fitter individuals have more surviving offspring, and fitness is measured by the amount of surviving offspring. No intelligence or purpose of any kind at work here.

 

I would suggest ignoring the concept of species since it is a fuzzy concept that simply allows us to name a group of individuals. When differences between groups of individuals reach a certain rather arbitrary point, they are considered a different species.

[dr.syntax]

you don`t seem ready for the answers

Edited September 23, 2009 by dr.syntax
decided against answering this post

[Pantaz]

I recommend The Blind Watchmaker by Richard Dawkins.

[Edtharan]

In the natural selection section of my biology book it says that several species originated from one species. Nature then selected who would survive and who would die out based on the strength of the species (the features that were most advantageous etc.) Here are my questions:

 

1. Where did all of the other species come from? Were they genetic mutations or were they modified? And if they were modified how were they modified?

The basic process works like this:

 

1: DNA is a set of molecules that can replicate

 

2: DNA encode the way an organism develops

 

3: Various chemicals, atomic and subatomic particle collisions and even mechanical forces can cause changes in the DNA molecule.

 

4: If the DNA is changed then this will change the way an organism develops (As DNA encodes this information - see point 2)

 

5: Not all individuals within a species have an identical DNA sequence (there exist variation amongst the individuals within a species). This is due to the fact that DNA can be mutated (see point 3)

 

6: If a species is spread far enough, then different groups of individuals within that species can exist in different environments and alongside different species than other groups.

 

7: These environmental pressures create different ways to exploit them, or avoid dangers within them (eg: different food sources or different predators).

 

8: An animal that is specialised for exploiting a food source or avoiding a predator will usually live longer, be able to compete better for mates and produce more offspring. These will cause the more specialised individuals to represent a bigger portion of the population of a group.

 

9: Interbreeding between these groups can often reduce the traits of specialisation of the offspring. This will make the offspring of those that interbreed between groups to be less specialised than the offspring of those within the group.

 

10: These less specialised offspring can not compete as effectively for mates or food and can fall prey to predators more easily. This will mean that these less specialised offspring will be wasted effort for the parents.

 

11: This wasted effort means that there is an evolutionary advantage not to interbreed between these groups and groups that have enough mutations to make this impossible will produce more offspring that will survive to breed and so will represent a larger portion of the group.

 

12: As the two groups can not (or will not) interbreed, they are effectively two separate species.

 

13: Over time the environments they are in will change (or they will move to new ones) and so the traits that make them able to best exploit those environments (or to avoid being exploited by predators themselves) will change. But, because they are no longer able to interbreed with the other group, and the other group are experiencing different environmental changes and challenges, they adaptations of this group will be different form the adaptations of the other group.

 

2. My book also states that there was descent with modification. How did these modifications come about? Did the environment trigger these modifications?

See points 1, 2, 3 and 4 above.

 

Because DNA direct the development of an organism, any changes to that DNA will cause the organism to develop differently.

 

Changes to DNA can come from many sources; from other chemicals, from impacts with particles that knock the DNA molecule around, from mechanical forces, or other organisms using these causes to directly change the organism's DNA (like with Viruses).

 

Also, with Sexual species (ones that combine parts of their DNA from parents), as they share only part of their DNA and combine them, this too can give variation between parents and offspring.

 

3. Doesn't this whole theory of nature selecting the stronger species favor creationism over evolution? My knowledge on evolution is rudimentary, but from what my book is telling me, there was no such thing as evolution. Several species already existed and the strong survived.

As I showed above, small amount of variation within a species and if that species is spread over a range with different environments in it, then this can lead to small adaptations that first allow the individuals to exploit that part of the environment better, then cause specialisation, then prevent them from breeding together, and then causing them to drift away from each other and the common ancestor.

 

None of this requires any form of intelligence or even purpose. It only requires variation (which has been well established) and that non random selection occurs (non random does not imply intelligence or even purpose.

 

For instance, if we were running away from a hungry Lion, if you were the faster runner because of your genes (eg: longer legs, better cardiovascular system, etc), then I would be eaten by the Lion and you would survive. This process of selection is non random, has no purpose and does not require intelligence to operate or cause it to be.

 

Evolution is an algorithm: think of it as a type of computer program (and it can in fact be created as a computer program and is used in many industries today from medicine to aircraft design). To say that Evolution can not work is to say that computers don't work (as clearly they do because you are using one to read this).

 

So "Evolution" can be mathematically shown to exist (just as 1 + 1 = 2 can be proven to exist). So any book that claims that evolution does not exist is therefore wrong (unless they can prove that 1 + 1 does not = 2 ).

 

If they are claiming that it can't be applied to living organisms, then this is a completely different argument.

 

However, an algorithm does not care what "Hardware" it is implemented on, so long as the processes required by the algorithm exist within that Hardware.

 

Evolution only requires:

 

1: Replication with variation

2: Non-random selection

 

As living organisms can be show to exhibit these properties, and the mathematics of algorithms say that anything that has these properties will be able to perform the algorithm of evolution, then it can also be shown mathematically that organisms can evolve.

 

This makes any book claiming that Evolution can't occur in living organisms false (unless they also can prove that 1 + 1 does not = 2).

 

To understand the mathematics of how algorithms work you need to understand the mathematics of Turing Machines (http://en.wikipedia.org/wiki/Turing_machine) and Universal Turing Machines (http://en.wikipedia.org/wiki/Universal_Turing_machine). Universal Turing Machines are the basis of your computer.