Solution-
Evolution is the gradual and orderly biological changes that result in the adaption of the species to the higher needs. For example – a classic example of the homo sapiens who evolved from the ape.
The species overtime adapts to environmental changes. For instance, giraffes evolved as long as they are because of the shortage of lower plants in the surrounding.
This evolution occurs through the process of natural selection ie. the traits that have a very high rate of survival tend to be passed on to the next generation of the species. For example, when there were no lower plants left in the biodiversity, only longer giraffes genes will be transmitted to the future generation. And hence the whole population will be adapted to the changes. Thus fitness is the inherent ability of the species to survive.
We evolved from apes and we have the following 3 distinctive features-
Our brain evolved into a bigger size with accelerated capacity to think perceive, understand and comprehend. More evolved cognitive skills including fine motor and gross motor skills.
Upright walking
More evolved hand with greater precision of the thumbs and fingers.
Our behaviours are highly complex and reasons are because of the variations in the brain and development of cerebral cortex, this is all because of the environmental demands. Some behaviours explicitely force for the evolution. Thus these evidences are enough to highlight that environmental demands lead to biological and behavioural changes over a long period.