Sunday, October 23, 2011

Giraffe - Evolution Run Amok


Have you ever sat around contemplating why a Giraffe has such a ridiculously long neck? Biologists will tell you that it gives them an evolutionary advantage to be able to eat leaves from the tops of trees that other species can't reach. That may be true however they also graze on grasslands that impala and kudu and a whole host of other antelope feed on. Some suggest that the long neck is an advantage in seeing predators in the distance. Yet there are a bazillion impala on the African savanna and they seem to survive just fine with all the predators out there and an impala is much shorter than a lion or a leopard.

And why is the giraffe built so off-center? Look at its front legs. They are several feet longer than their hind legs. Is that an adaptation for holding up their massive neck so they can eat those leaves at the top of the tree? And why are their hind legs so much shorter? Maybe that is an adaptation to balance out their gargantuan neck?

And what's up with those wimpy horns? They seem to serve no purpose at all. Certainly any marauding lion is going to laugh itself sick if a giraffe takes a swipe at it with those wimpy horns. And why is a Giraffe's tongue black? Do they think it will serve as camouflage while they eat those tall leaves at night?

I started thinking about these things seven weeks ago today when I saw my first giraffe in the wild near Punda Maria Camp in Kruger National Park.


My first wild giraffe
Predictably it stood in the scrub forest with its neck and head towering over the trees beneath it. He/she was perfectly situated to gorge on as many tree-top leaves as it could swallow.

I sat and watched the giraffe for maybe 15 minutes as it poked around in the forest. Later in the day I found more giraffe including one that was splayed out across the savanna trying to get a drink of water. I almost felt sorry for it having to go through all of the contortions just to get its mouth close enough to the water to have a drink.

Giraffe drinking - or trying to drink - water

As with my elephant experiences looking at a giraffe made me feel like I was watching the movie "Jurassic Park" one more time. They simply defy logic when you see one loping along (and they can lope pretty fast) through the thorn forests. They do so very quietly as well. How something weighing 2000 pounds and standing up to 16 feet tall can be so quiet when it moves is another mystery of this animal.

I remember well the day when I was home from college during graduate school when a pair of Seventh Day Adventists showed up at our farm determined to save me from an eternity of fire and damnation. The topic that got them excited was evolution. I was taking a graduate course in evolution at the time and luckily I had my facts and figures down perfectly. They didn't stand a chance.

The bible thumpers were excited because I stated matter of factly that if you read Genesis 1:1-7 objectively it maps out the course of evolution from the simpler life forms to the more complex life forms ultimately resulting in humans. Of course you can interpret anything in the bible to suit any topic you might be discussing but I didn't mention that. All I heard from the bible thumpers was that "I did not evolve from an ape." Well, yes you did but what's so bad about that? George W. Bush is living proof that humans and chimpanzees are first cousins however Dubya wasn't an issue at the time.

I asked the thumpers to tell me some of the characteristics that all mammals have in common. Things like hair on their bodies, and mammary glands, giving live birth, a lower jaw made of simple bone, the ability to replace teeth at certain ages, the ability to regulate their body temperature, a four chambered heart, and seven cervical vertebrae. All mammals possess these characteristics and no group of animals other than mammals has all of these characteristics.

So I asked the thumpers how many chambers are in a human heart. They had no idea. Then I asked them how many chambers were in a chimpanzee's heart and how many in a giraffe's. They didn't know. (the answer is four). I asked them a number of other questions and then said "So, how many vertebrae do you have in your neck?" They didn't know that they had seven. I then asked "How many vertebrae are there in a mouse's neck?" They guessed three but the answer was seven. I then asked "And how many vertebrae are in a giraffe's neck?" They said 20 but the answer is seven just like there are seven in the neck of a chimpanzee.

After discussing these biological facts a bit more and pointing out that in the biological scheme of things we humans have a lot in common not only with our first cousin the chimpanzee but also with a mouse and with a giraffe the thumpers had had enough. We had been debating for three hours and despite all the facts in front of them they refused to believe them. Finally I was asked if I was concerned what would happen to me when I died. I smiled and said "I want to be buried on the plains of Africa next to a giraffe so his seven neck vertebrae can play pool with my seven neck vertebrae any time they want to." Clearly flustered the thumpers threw their hands in the air, yelled "there's no hope for you young man" and left. Some giraffe somewhere in Africa was probably smiling as the two thumpers stormed out of our back door and then drove away.

I saw giraffe every day I was in Kruger National Park and never once tired of looking at them. They are such a biological oddity it was impossible not to want to look at them. One day while watching one chewing its cud (giraffes are the largest ruminants on earth) it dawned on me. A giraffe is like a Jersey cow on a Barron County Wisconsin pasture chewing its cud and watching the day go by. The only difference is that a giraffe neck is about 80 times longer than a Jersey cow's neck.

The picture below is my most favorite one from the trip. I found a group of seven giraffe (the largest group I encountered) by the side of the road near the Letaba Rest Camp one day. Predictably they were just chilling out eating acacia leaves, chewing their respective cuds, and just being giraffes. The one in this picture had a flock of yellow-billed oxpeckers on its neck. There were probably 20 of those birds picking lice and ticks from the skin of the giraffe's enormous neck. Every so often the giraffe reached the limit of his tolerance and would shake his head and neck like a dog (but in much slower motion) sending the oxpeckers off in a frenzy of feathers only to land back on the giraffe a few seconds later.

If you look closely at the picture below you can see not only the intricacies of the giraffe's neck but you can also see several ticks by its ear and near its horn there is a yellow-billed oxpecker waiting patiently to dine on ticks.

Close up of a giraffe's head. Note the ticks by its ear and the yellow-billed oxpecker waiting for a chance to dine on them

Among the 49 species of mammal I saw on my South African journey, I have to say that its a toss up between African elephant and giraffe for my most favorite. And although neither could eat me (both could crush me like a bug however) I think I enjoyed them so much beause they both define evolution run amok.

2 comments: