What is the least likely reason why persons from populations that have been living near the equator are darker on average than persons from populations living further from the equator?

food is a least likely reason

Explanation: The equator is an imaginary line that divides the earth between two halves (north and south).

The polar settlers or those that are farther away from the equator eats food that contains vitamin D. They get the vitamin from food as an alternate source.

The tropical settlers feed mostly on foods that are high in carbohydrate.

However, melanin is a pigment that is usually brown, it is a natural sunscreen that sheilds tropical settlers from the many harmful effects of ultraviolet (UV) rays.

organ system-an organ system is a group of organs that work together to perform one or more functions. each does a particular job in the body, and is made up of certain tissues.

cells use diffusion to get substances in and out of themselves. that diffusion will occur across the cell membrane or the outer covering of the cell. because we are talking about the surface of the cell, surface area and volume are  important factors here. as a cell increases in size, its surface area and volume increase as well.  we call that the surface area to volume ratio (sa: vol).  but the catch is that  volume increases at a greater rate than surface  area. in other words, as a cell gets bigger, the sa: vol gets smaller. so a really small cell like bacteria is mostly cell membrane (surface) with very little contents (volume). a really big cell like an egg, is mostly insides with a super thin membrane. so what ends up happening is that the cell cannot efficiently diffuse all of the stuff it needs in/out to survive. therefore cell size is limited to about 100mm. so how do we make organisms bigger than 100mm? cells divide! by dividing and becoming multicellular, organisms are able to grow!   check out the diagrams i attached to see the effect of sa: vol. i hope this ! good luck!