evolution - Are humans evolving since their first appearance?

Is the evolution a very prolonged progress, or are we going to witness further evolution of the human species?

If so, in which direction? Are there any widely predicted changes for humans?

Answer

Humans are still evolving.

If you have a proper understanding of evolution you will not doubt this....

What is evolution?

"Evolution means change, change in the form and behaviour of organisms between generations. ... When members of a population breed and produce the next generation we can imagine a lineage of populations, made up of a series of populations through time. Each population is ancestral to the descendant population in the next generation: a lineage is an ancestor-descendent series of populations. Evolution is then change between generations within a population lineage."

Evolution is simply a process of change, which Darwin called descent with modification. It is a change in trait values of populations over time. It results from four mechanisms: mutation, migration, drift, and selection. The first three lead to random change from one generation to the next, which may increase or decrease fitness, while selection will generally lead to adaptation.

How do we know evolution still occurs in modern humans?

Well human traits (characteristics like hair colour, height, eye colour ...) are often determined, to varying degrees, by genetic information. That information is passed from parent to offspring (inheritance) and that information can accumulate new variation (e.g. by mutation), while some variation can be lost from the population (by drift, migration, selection). These are the conditions required for evolution. Therefore, from one generation to the next, population trait values can change.

How will humans evolve in the future?

Difficult to say, evolution is a quite random process and difficult to predict. However, the process of adaptation (the result of genetic variation and selection) is a little more predictable. Following from the above, if there is genetic variation in a trait then there is a good opportunity for it to evolve by selection (Fisher's Fundamental Theorem). For example, we now see more women choosing to have children later in life, this means selection will be stronger against genes which cause early-life mortality in women and selection will favour genes that slow reproductive ageing in women. Conversely, modern medicine is reducing selection against genetic diseases as we are better able to combat them, so we will probably evolve to show genetic diseases more frequently - selection against genetic diseases is weaker, therefore disease causing mutations can persist more easily in the population, see mutation-selection balance.

If you are able to prove that a trait is subject to selection and that there is genetic variation then you should be able to say that, in the short term at least, evolution in that trait will proceed in a predictable manner. Here are some posts (1, 2) about evolution in modern humans, open ended evolution, and why selection might not produce the predicted response.