This is one of the key sentences of this interesting documentary about evolution. I invite you to watch this video and then try to answer the question.
Don't worry if you don't understand all, just try to catch the general ideas about how the researches work, and how different species drive their evolution through their sexual behavior.
If you need some help you can read this document.
When we think of evolution, we think of it occurring over millions of years. However, it is important to realise that evolution can and does occur over relatively short periods of time. For example, bacteria have developed resistance to many antibiotics through changing their DNA or acquiring new DNA over a period of a few years. About 5,000 years ago, humans in Europe developed the ability to digest lactose into adulthoold. This gave them a selective advantage over people who were lactose-intolerant, as they could drink cow's milk without any adverse effects, or at least, not inmediately dangerous ones.
Many new changes in a group of organisms over a long period of time will eventually make it so different from the original organisms that they can become a new species, though these organisms must be able to produce fertile offspring. DNA is very important given the fact that a change in the structure or amount of the genetical material (mutation)can drive to a new characteristic sometimes good, sometimes bad.
On the other hand, the environment plays a fundamental role in this process though the natural selection, by which particular traits become more common in a population due to that trait being advantageous to the species. Natural selection was first described by Charles Darwin in his 1859 publication, On the Origin of Species.
Because of sexual reproduction and random mutations, there is a variation in populations of all species. Most of the time, these variations don't affect suvival in the habitat, but occasionally one member of a group has a faster rate of reproduction or a special ability to scape from the conditions that threaten the existence of the population. The phrase 'survival of the fittest' sums up the process accurately.
However, after watching the documentary, you must be able to understand how behavior influences evolution, especially in human beings. Which is your conclusion in our case?
Now, just to review the key words try this activity