How does Christianity explain the different races? And what about the fact
that early humans were shorter on average? My friends say that we have
evolved to grow taller. Is this true?

To put it simply, the Bible does not explain the different races. The
difference between the races has to do with genetic material and DNA,
which the Bible clearly does not discuss, as the original readers did not
even have such vocabulary. Do not expect to find an explanation of the
origins of race in the Bible, and do not listen (except with an extremely
skeptical ear) to those who attempt to find biblical support to some sort
of theory of the origin of the races. Unfortunately, some in the past have
abused the story of Noah’s sons to support some sort of racist agenda. The
fact is that the different races have virtually identical genetic
material. For example, there is far far more variety in genetic material
amongst Native Americans themselves, than there are differences between
the races.

Were earlier humans shorter? Fossil remains show that on average, earlier
humans were significantly shorter, but there is some evidence in the other
direction. To make it simple, let us say that on average, earlier humans
were shorter than they are today. Even one hundred and fifty years ago in
the USA people were on average several inches shorter than they are today.
In fact, when immigrants to a first world country arrive from a third
world country, they are on average several inches shorter than their
“Western” contemporaries. Interestingly, within a generation or two these
former immigrants seem to catch up to Westerners. From this data, it would
appear that the fairly recent dramatic increase in average height is not
due to any genetic change, but is rather due to a change in diet. In most
of the third world (and in the entire world before modern times) a fairly
poor diet?especially one poor in protein?has tended to produce much
shorter people.

In summary, your friend is correct in claiming that humans are on average
significantly taller than their predecessors. However, the increase in
height observed over the last two centuries or so does not represent
evolution as much as it illustrates the effect of a well-balanced diet
which is high in protein.

John Oakes, PhD