Can evolution explain why men are taller than women and have deeper voices?

Thee can be several independent factors that play a role in human differences between the sexes. The body size difference and the hair patterns may be due to different selections acting. Technically this is called dimorphism, two forms, where the two sexes do not have identical body sizes, colorations, or courtship ornaments (antlers, feathers, or coloration).

An extreme dimorphic size example is with elephant seals. In the other direction it is impossible to sex some birds without examining their internal organs because the two sexes appear identical to us. To understand the possible advantages of dimorphism it must be possible to assess the reproductive strategies variable success rates.

In elephant seals the size is the key factor. A single male seal may go on to gather a large harem and inseminate many females every year if he becomes big enough to out compete all the other males. Here many males may have zero reproduction but a few will have a huge success. These animals do not share in rearing the young. Females are guaranteed a steady moderate success. Since they actually give birth their reproduction rate is limited by how much effort they put in to growing and caring for each young. Some species have the males go for the lottery route to reproductive success while other species have monogamy and moderate success for both sexes. Here the male stays with his investment and helps rear the young. In these instances the two sexes are most likely to be very close in size.

Humans clearly show some of the dimorphic characteristics in body size. Humans are set somewhat between with some level of monogamy but also some tendency towards harems (polygamy). Some share in rearing the young but some do not. Humans can clearly select between several options unlike many species.

There is a list of dimorphisms in humans at :

wikipedia.org under Sexual dimorphism

Early hominid sexual dimorphism

http://www.pnas.org/cgi/content/extract/100/16/910...

http://www.evcforum.net/cgi-bin/dm.cgi?action=msg&...

http://www.unl.edu/rhames/courses/male_facial_beau...

http://www.sciencecodex.com/how_sexual_selection_s...

The differences in body hair patterns and colorations can be due to yet another factor. Partner selection can lead to another kind of physical variation. Peacocks and other birds are evaluated by their tails excessive appearance by the peahen or female birds. The idea here is the male demonstrates his potential genetic quality by being able to survive against predation despite the drag of carrying around this heavy tail. Male Mallard ducks are similar in that they produce iridescent feathers during the mating period. These feathers require very healthy birds to grow the best. Birds with parasites can not produce them. This way the females mate with the healthiest or strongest males. This is called sexual selection. Humans definitely use this in selecting potential mates and is likely to be the basis for that feeling of instant connection some people experience. They have just seen a person who visually qualifies as the ideal mate. This is possibly why certain rare color variations like red hair are kept. People prefer the rarity of the color so it is actively selected for. This is why there are so many eye and hair colors in European ancestry. Given the choice people prefer the rare color.

http://pages.globetrotter.net/peter_frost61z/Europ...

Once the genes for skin and eye colors appeared they became subject to natural selection.

http://www.gnxp.com/blog/2005/08/beyond-mc1r.php

http://www.ananova.com/news/story/sm_80720.html

I think men and women are two different species. Ha ha. It's a little joke.

I don't know the answer to your question but I saw a show on primates awhile back that was pretty shocking.

Among the chimpanzee and great ape family the most harmony & joint cooperation between the male and female partners was shown in a species of orangutan with least variation in size, male to female. The greater the size difference male to female within each species, the more lack of cooperation, poor family relationships and fighting was evidenced.

i think it has to do with natural selection. and then evolution