2) what environmental pressures in the past do you think were most important in shaping the human species as it exists today?
4) what environmental pressures do you think may affect humans as earth becomes more populated with humans in the future? explain how these pressures may affect human traits.
me.

Some environmental pressure in the past that help shape human species are:
a. the search for food and its development
b. the presence of disease and health concerns
c. the development of materials and mechanisms that can help make work faster

These environmental pressures may affect humans as it grows into a larger population because these are all basic needs that need to be met on a daily basis. Having a large number of people means that supply might eventually become too limited. 

The proton has a positive charge while the neutron has no charge they both make up the nucleus of the atom while the elections have a negative charge and surround the nucleus of the atom. the protons and electrons are used to calculate the atom's mass whereas the neutrons don't affect the mass