Humans and other animals

There's the familiar debate about the relationship between human beings and other life forms on this planet.  In particular, people wonder about the difference between human beings and everything else.  What does this difference amount to?

Generally speaking, there are two types of differences: differences of degree, and differences of kind.

Differences of degree occur when you have two things that belong to some relevant category, but differ in magnitude with respect to some variable shared by both things.

For example, a pin prick and a migraine headache are similar in that they are both types of pain.  However, they differ with respect to the intensity of the pain.

Differences in kind occur when you have two things that don't both belong to the same relevant category.  For example apples and rocks differ in kind if the relevant category is fruit.

Having set this up, how do we describe the difference between humans and other life forms?  Is the difference primarily of degree or of kind?

Most everyone agrees that humans share a lot with other animals.  Humans are carbon based life forms that are sustained via air, water, food.  Human are born, reproduce, and die.  Furthermore, humans share a lot with mammals.  Humans are warm blooded, have body hair, reproduce sexually and via birth.

Some, however, go further and say that although there are lots of similarities between humans and other animals, humans still differ in kind.  What does this difference amount to?

Traditionally this difference amounted to something non-physical, like a soul or a spirit.  Human beings are somehow made in the image of God, whereas other animals are not.  This difference is significant in that it is normative, rather than merely descriptive.  According to many religious traditions, human beings are different in a way that makes them "higher" or "better" than other life forms on earth.

Nowadays there are more people who don't affiliate with a particular religious tradition.  Among these, many reject the idea that there is some non-physical aspect of humanity that separates it from the rest of life on Earth.  

Suppose that we accept the claim that there is no difference in kind between humans and non-human life.  There's an issue that we have to deal with.  We observe lots of things that humans do that other animals either don't or can't do.  Here's a sample list.

Advanced mathematics

Poetry

Moral reasoning

Philosophy

Classical music

Abstract art

Religion

Travel to outer space

Engage in nuclear warfare

Make iPhones

Form democratic governments

What explains the fact that humans do these things and other animals don't?

One route is to say that the difference between humans and other animals is that of degree.  Animals can communicate, cooperate, and build stuff.  They just can't write poetry and build skyscrapers.  Perhaps the difference between humans and animals is more like the difference between an adult human and an infant.

Explanation by difference of degree is kind of satisfying, but not wholly.  First, the gap in intellectual ability between humans and whoever's in second place (gorillas, chimpanzees, dolphins, etc) seems incredibly vast.  Why are humans so far ahead of everything else?  

Second, we don't see any other species doing anything remotely close to what humans are doing.  Why is it that just humans are the ones that figured out how to get to the moon?  Why haven't other species developed in similar ways?

Evolution and the Christian doctrine of Imago Dei

Aside from exegetical issues surrounding the first few chapters of the book of Genesis, there really doesn't seem to be much conflict between the idea that a divine Creator exists and that life as we know it is the product of an evolutionary process.  It doesn't seem so hard to imagine that God set the initial conditions and started the process off, perhaps making a few tweaks and adjustments along the way.

One area that does seem to create some tension, at least in my mind, is the doctrine of Imago Dei.  This Christian doctrine roughly holds that humankind is made in the image of God.  What does this mean?  Since Christian orthodoxy holds that God is not a physical entity, being made in the image of God can't be interpreted as being made in the physical image of God.  If that's the case, then by "image" we must mean some kind of emotional, intellectual, spiritual, or volitional faculty (or perhaps all of the above).

If it is indeed the case that man is made in the image of God, then this question is put to those (including me) who believe in the truth of evolutionary theory.  According to evolutionary theory, mankind is a descendant of a number of lesser developed species.  If this is so, then at what point was the image of God imparted in man?  Humankind is a descendant of early one celled organisms.  Surely these organisms did not have the image of God.  The same could be said of other species that are part of humankind's evolutionary lineage.  One might point out that the image of God was imparted when the species Homo Erectus evolved to the species Homo Sapiens.  However, this transition was gradual.  Can we point to some exact event where the image of God was imparted?  If so, where and why that event?

For those who interpret the first few chapters of Genesis literally, the answer to this question is simple.  The image of God was imparted on the sixth day of creation when God created humankind from dirt and breathed the breath of life into them (or at least him).  Here there is a specific event that can be pointed to as the event where the image of God was imparted.  Of course, this answer comes at the cost of a highly implausible account of the Earth's origins.

So suppose that you identify as a Christian whose beliefs are more or less orthodox.  Suppose also that you are convinced by the theory of evolution as accurately describing the history of life on Earth.  How do you resolve this apparent tension between science and religion?