Monthly Archives: January 2015

ape-eye-montageLooking a gorilla or chimp in the eyes is – for most humans – a profound experience. Ape eyes are so enigmatic and it’s obvious that we have much in common in the way of facial expressions and behavior.

Do you like being stared at? Probably not. In most primates a direct stare is a threat, while looking down or away is submissive. Being able to read the eye movements of others is very important in social communication. This is easier to do if the color of the iris contrasts with that of the sclera – in our case, the sclera is the “white of the eye”. In other members of the hominid family (apes and us) the sclera is usually darker, but occasional mutants show a white sclera too. Why might it be an advantage to have a white sclera? Why do some people dye their sclera black?

Here is a fun quiz for all of you who think you know how to tell about a person or animal from the eyes. See if you can guess the owners of the eyes at left. (Answers below)

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                                            answers: orang, bonobo, human, chimp, gorilla

Graphic showing family tree of apes and man.

Ape family tree, by David Bygott

 I just led a Great Ape safari through Uganda and Rwanda to see chimps, gorillas and many other primates. It was a thrill to look into the feisty eyes or a chimp and the calm brown eyes of a gorilla and feel the connection – kin – but not quite. I was especially aware of our differences because one of my guests had said at the beginning of the safari:

“I came on this trip in order to see our closest ancestors.”

“No.” I had to reply. “None of the great apes alive today are our ancestors. Our ape ancestors have been dead for over 6 million years.”

He looked puzzled but eager to understand. So let’s try to make it clear how we are related. First, we humans and all the monkeys and apes are primates. Primates are an order of mammals with binocular and color vision and grasping hands. Primates split off from the ancestral mammals about 60 million years ago and diverged into various kinds. Through fossils and DNA we can trace the ape line back about 25 to 30 million years. The “ancestral ape” had no tail and was larger and longer-lived than other primates.

The apes continued to split; gibbons and orangutans went their own special ways and the other ape line kept evolving too. By about 9 million years ago a gorilla line was established and the rest of the ape-like beings evolved into two major types: chimps and hominins. Today we have two living representatives of the chimp line – chimpanzees and bonobos. Since Neanderthals died out relatively recently, that leaves only humans as representatives of our hominin line – the upright walking apes. So apes are our relatives but NOT our ancestors.

Here is a family tree with the living apes that shows the very approximate times when we left the other primates. A family tree is like an African flat-topped acacia, whose gnarled branches separated long ago and all the little twigs of the canopy have been on earth for the same amount of time. We humans are not at the top of a tree like a pine, with all other creatures down below us. I think it is very important to realize that all living beings are at the same level, we are all survivors through time. Gorillas and chimps are definitely our surviving relatives, but not ancestors.

 

Jeanette wearing giant model bat ears

Some people are really sensitive to noise – Jeannette with simulated bat ears at Arizona Sonora Desert Museum

Here in Tanzania I am reminded of peoples’ different tolerance of noise. Back in Tucson, our close neighborhood has firm rules about noise pollution. No power tools or loud music between 10 p.m. and 8 a.m. One new resident complained angrily to the community about a loud rattly power tool being used on a metal roof at dawn – the culprit was a Gila woodpecker, who had found this to be a much more effective territorial display than drumming on a dead tree!

In our gardens, leafblowers are banned. However, we dispose of our tree prunings on site with a rather noisy chipper that converts them into mulch. Recently I was running it late in the evening and next day we received a complaint from a neighbor about 300 yards away. We worked it out amicably, that I wouldn’t chip after dark. So there are layers of noise prevention – mutually accepted constraints, policing by neighbors, and if that fails, policing by the police.

In the suburb of Arusha where we’ve been staying (picture), it’s a different story. Moshono Juu is about as densely populated as our Tucson suburb, but people are either more tolerant, less organized or both. A lot of the noise is due to religion, particularly evangelical preachers. They get behind a powerful amplifier and pour hellfire on the whole neighborhood. Last night it woke us up about 2:30 a.m. An insane bellowing in Kiswahili, the same phrases repeated over and over, definitely channeling a god of hate and vengeance rather than love. I wondered what sleepless cult attended this harangue. Would they be stoked on drugs or booze to endure such cacophony? And would our PC friend Dave call it “entitlement” if I, a mzungu (paleface), were to walk into an African village and demand a good night’s sleep? But then, what if other neighbors also wanted to sleep, yet didn’t dare make a fuss? This must be a powerful cult indeed. Would a wild-eyed enraged congregation fall on me with rocks and cudgels for interrupting their religious ecstasy?

Eventually, insomnia and curiosity won. I took a big maglite that could double as a club, and slipped out into the moonlight into unscripted territory. The gravel road down the hill was treacherous, like walking on ball bearings. The demonic sound grew ever louder. Half a mile away, its source was a low barn of poles and tarps with a tin roof. A simple church. Easy to burn down – but I had no matches. A long white power cable connected it to a nearby hut – easy to cut, if only I had a panga. OK, I get cranky when sleep-deprived; those are last resorts. Let’s first assess the strength of the enemy and try a polite request. The doors were shut so I peered through a window opening and was amazed. The benches were empty! There was a makeshift altar and a table full of sound equipment. Taped hymns were playing, and a lone young man in a shabby Tshirt was pacing to and fro, yelling into his microphone. I leaned in through the window and he turned down the sound and came over. He looked sheepish.

“Please can you make less noise?” I asked. “It’s 4 a.m. and we can’t sleep!”

“Where you from?”he asked.

“Up the hill. It doesn’t matter. Can’t you let us sleep?”

I wished him goodnight and left him leaning on the sill, his head bowed, perhaps seeking divine inspiration. All was quiet as I trudged up the hill. Then a short final outburst, slightly less loud, barely enough to blister paint or singe nearby trees, and he was done for the night. It was nearly 5 a.m.

Photo of baobab and saguaro plants, with insets showing their flowers

Baobab (left) and its flower (top centre); saguaro (right) and its flower (bottom centre).

We have been privileged to share years of our lives with both baobabs and saguaros, giant plants that dominate their dry landscapes. The baobab tree (Adansonia digitata) is one of the icons of Africa, with its vast swollen trunk and smooth bark. To St-Exupery’s Little Prince, baobabs were a metaphor for something bad which must be nipped in the bud before it takes over your little planet. In reality, they are magnificent beings which offer bountiful gifts. Their trunks, often hollow, can house bees, barn owls or even people. Their tender leaves are good to eat. Their fleshy white flowers bloom at dusk and offer rich nectar to the bats that pollinate them. Their fruits are useful woody gourds containing nutritious nuts wrapped in a frothy packing rich in Vitamin C, a popular snack for people and wild animals. Their fibrous juicy trunks are used to make string, but are useless as timber. More useful alive than dead, over much of their range they are the only native trees left standing, and they may live for over a thousand years. They are respected and revered; the Tanzanians say “Kila shetani ana mbuyu yake” – every spirit has its own baobab tree.

Half a world away, in the Sonoran Desert of Arizona and northern Mexico, tall saguaro cacti (Carnegiea gigantea) raise massive spiny arms to the sky. A mature saguaro may stand 40-60ft tall with more than 25 arms, and may weigh more than two tons, somehow supported on a base only a foot wide. Inside each stem or arm, a cylinder of vertical woody ribs provides support. The desert people, Tohono O’odham, venerate saguaros and see them as partly human. In spring the saguaros wear beautiful crowns of white flowers, also pollinated by bats. Just before the summer rains, the O’odham and the desert birds harvest their fruits, filled with tiny black seeds in sweet crimson pulp. When we moved to Arizona, one of our O’odham neighbors showed us how to make a long pole from the ribs of a dead saguaro, and knock down the abundant fruits from 30 feet above our heads.

Saguaros grow slowly, usually germinating in the shade of a paloverde or other ‘nurse tree’ where a bird dropped the seed. They may take 10 years to grow 1.5″ high, and can live for up to 200 years. Baobab seeds must be brutalized by passage through an elephant’s jaws and gut in order to germinate. Their seedlings seem to grow best amid dense thickets of other species, where browsing animals can’t reach their tender leaves.

Both saguaros and baobabs have extensive shallow roots, spreading sideways at least as far as the plant is high, and may have a deep tap-root too. When it rains, both plants can rapidly absorb water, then store it for a long time. To conserve water, their leaves are reduced. Saguaros have no leaves at all, photosynthesizing with their waxy green pleated stems. Baobabs produce leaves only during the rains, standing bare for much of the year – but if you scratch that gray or pinkish bark, you will find bright green chlorophyll just beneath it, proving that the “upside-down tree” is not as dead as it looks.

Hug a baobab’s vast trunk – it may take 20 of you to encircle it – and you may feel or hear the wind thrumming through its bare branches. But don’t try hugging the saguaro, just admire it from a distance.