I am almost secure that this affirmation aren't exactly true but I want to know which of these statements is more near to a description of how evolution works:

  • The evolution has an exactly target and always progress to it, each generation the childs are more close to make complete a certain task, that is beacuse evolution is like "directional".
    For example: The task is be 10cm taller. Each generation the race become 1mm taller up to complete the task.
  • The evoultion is random but the specie (or natual selection) try to reach a target, each generation has random traits but only benefical traits tends to "survive" and get offpring.
    For example: In order to survive the task is be 10cm taller. Some childs are half cm taller and other childs are half cm smaller, the last ones die naturally and only the taller ones survive enough to get offspring.

closed as off-topic by anongoodnurse, Bryan Krause, David, James, AliceD Oct 4 '17 at 21:59

This question appears to be off-topic. The users who voted to close gave this specific reason:

  • "Homework questions are off-topic on Biology unless you have shown your attempt at an answer. For more information see our homework policy." – anongoodnurse, Bryan Krause, David, James, AliceD
If this question can be reworded to fit the rules in the help center, please edit the question.

  • 2
    $\begingroup$ This seems like it's some sort of homework assignment, though I am afraid even the better of the two is hardly any better. $\endgroup$ – Bryan Krause Sep 13 '17 at 22:32
  • 1
    $\begingroup$ One is better but is still awfully unclear, poorly phrased and misleading. I don't feel that if you were to know which one is better, it would not help you much to get basic understanding of evolutionary processes. The best for you is to start with a short and easy intro course such as Understanding Evolution by UC Berkeley for example. $\endgroup$ – Remi.b Sep 13 '17 at 22:56
  • $\begingroup$ @BryanKrause given how bad the phrasing is, I think we can be clear this not a homework and could answer which one is better, right? So, here we go: The second one is slightly better! $\endgroup$ – Remi.b Sep 13 '17 at 22:56
  • $\begingroup$ @BryanKrause, that isn't a homework! We don't have biology in school, it's only a curiosity of me. $\endgroup$ – Ender Look Sep 13 '17 at 23:40
  • $\begingroup$ @Remi.b, sorry for my grammar, english isn't my main language. It's a curiosity that I have, not a homework. $\endgroup$ – Ender Look Sep 13 '17 at 23:40

The second is marginally better because it mentions randomness and emphasizes differential survivorship, but the parts about "trying to reach a target" and specifying a particular "task" are misleading at best. I would rewrite the statement as follows (I have edited for grammar, spelling and style as well, but emphasize more substantive deviations with strikeout for omitted parts and boldface for added parts). The substantive edits change the meaning of the statement significantly: most evolutionary biologists would be very uncomfortable with the second statement as written above (setting aside any grammatical issues).

Evolution is has a random component but the species (or natural selection) tries to reach a target, may result in directional change: each generation has some random variation in traits but only individuals with beneficial traits tends to are more likely to survive and produce offspring. For example, In order to survive the task is be 10cm taller. taller individuals survive better than smaller ones. Some offspring are a half cm taller and other children are a half cm smaller; the latter die naturally and only the taller ones survive long enough to produce offspring.

I would probably say "offspring" rather than "children" in a technical context.

Note also that this emphasizes evolution by natural selection; broadly speaking, there are many non-adaptive processes (vicariance, drift ...) that also lead to evolution (change in gene frequencies between generations).

  • 1
    $\begingroup$ I would remove Evolution is random or maybe jsut edit it to Evolution is partially stochastic or even better Evolution is not a purely/uniquely deterministic process or even Evolution is the results of a number of processes, some of them being deterministic, some being stochastic. Good answer otherwise +1. $\endgroup$ – Remi.b Sep 13 '17 at 22:59
  • $\begingroup$ Thanks for the answer. Sorry my poor grammar, english isn't my main language. $\endgroup$ – Ender Look Sep 13 '17 at 23:43
  • 2
    $\begingroup$ @EnderLook I just want to clarify for you especially as ESL/ELL, that this answer is correcting more than just grammar. $\endgroup$ – Bryan Krause Sep 14 '17 at 1:42
  • $\begingroup$ Don't worry about the grammar, by the way. I modified it because I'm a perfectionist, but there's nothing wrong with trying to express your ideas (my second-best language is much worse than your English). $\endgroup$ – Ben Bolker Sep 14 '17 at 1:58
  • $\begingroup$ @BryanKrause, I know, I am no so stupid ;). $\endgroup$ – Ender Look Sep 14 '17 at 2:08

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