Does evolution have a direction?
Evolution has every direction as it explores all possible life forms regardless of the environment’s limitations. However, it is possible to isolate a specific lineage over a specific period of time, and identify certain trends that might go in a particular direction. These trends do not last forever as they will eventually reach a limit due to environmental selection pressures, reverse, or end when the lineage becomes extinct.
There has been a general trend for the most complex lineages to become more complex over time, but this trend starts with long plateau periods. There is no noticeable difference in complexity between a Tyrannosaur and a Lion, for example. The numbers of these complex lineages, of course, are very small in comparison to the rest of life on earth. This means that that they don’t affect the average complexity by any measurable amount. Bottom line, the reason for this trend represents an inevitable consequence of evolution moving in all directions simultaneously.
This is a great question. According to science, evolution has no direction. Once a species reaches a steady state in a new environment, genes randomly vary features around a point that’s optimal for the environment. It’s impossible to predict how the environment will change in the future, if at all. Nature has allowed species to continue varying features that include bigger and smaller, more and less. Unlike human designers, genes don’t care about what humans would see as waste.
Why do we see a movement towards a greater complexity?
This is essentially because genes vary or mutate features that already exist. Nothing starts making features out of nothing. For example, hair is just altered skin cells. If you study comparative anatomy, it will become obvious that genes are working with what’s already there. An example of bad design is Derek Johnson’s answer to ‘Why is it so hard for many to believe that the Earth and mankind were designed?’ https://www.quora.com/Why-is-it-so-hard-for-many-to-believe-that-the-Earth-and-mankind-were-designed/answer/Derek-Johnson-42
The interesting fact about genes varying and mutations is that a feature that was favourite for a specific purpose – feathers may have increased warmth – end up serving another purpose – like flying.
What about perfection?
We can talk about fitness – the ability to survive in order to pass genes onto offspring. While others interpret that as ‘perfection’ this is merely an illusion. It’s the end effect when death kills the individuals with features that don’t work in that specific environment.
Why is there no record of devolution but always extinction?
Any features that require a great amount of energy and is prone to injury that is no longer needed, gets removed. Death kills off the individuals who can’t survive, removing these genes from the gene pool. Genes rarely start from scratch like I already said. They repurpose what is available.
By definition, evolution only has a direction looking back. The changes observed in heritable traits in a population over time are generated by the randomness of mutation. In my opinion, evolution does have a direction. The direction that humanity is taking represents the proof that evolution has a direction. One can see that the journey of the universe from a single cellular organism to a complex human being who is aware about its existence is linear. But that does not mean the other lineages of evolution have stopped either.