Evolution

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.

 

Dense crowd of Lesser Flamingos in lake.

Dense crowd of Lesser Flamingos in Big Momella Lake, Arusha NP

Everyone loves flamingos, those bundles of pink plumes on stilts. People on our safaris always want to find and photograph them. Here in Tanzania, at Arusha National Park near Mt. Meru, there are soda lakes where flamingos cluster. Flamingos are beautiful, yes,  and are also highly evolved to exploit their unique habitats – lakes full of algae and small crustaceans. They feed with beaks upside down, straining this food from greenish looking water. The chlorophyll of the algae contains carotenoids, pink or orange compounds which are deposited in flamingos’ plumage. Lesser flamingos, who feed directly on algae, are pinker than greater flamingos who eat brine shrimps. The quality of their shallow watery ‘pastures’ constantly changes, so they flap from lake to lake in the rift valley seeking the best food. We used to live on a flyway between Lake Eyasi and Lake Manyara, and often at night we’d see and hear their honking V’s passing over. These strange birds do amazing group parades, chorusing while marching, and they build crusty crater-like mud nests in the middle of desolate caustic lakes.

Lake Momella in Tanzania with dense fringe of flamingos

Flamingos fringe one of the Momella Lakes

Here I want to share a  fact about these fascinating birds. Researchers in 20 nations spent four years on a project to sequence the entire genomes of 48 species of birds. One of the results is that flamingos are closer relatives to pigeons and grebes than to look-alikes such as egrets and storks.  Another surprise was that the chicken seems to be way back there in the genome line, closer to the original bird stock than anything except ostriches.  Studies on bird evolution continue to evolve!

 

The Crimson Wing: Mystery of the Flamingos  is a wonderful film produced in 2008 by Disney.  If  you missed the TV presentation maybe your library has it. This link tells you more about the film.

Close-up of Lesser Flamingo head

A Lesser Flamingo’s bill is all dark red, and its plumage is rich pink.

Close-up of Greater Flamingo head.

A Greater Flamingo’s bill is pink with a black tip, and its plumage is paler.

Feral male jungle fowl

Feral Jungle Fowl, Po’ipu, Kaua’i

This is a fun extension to Safarizona territory – prompted by our November visit to Kaua’i Island in Hawaii. Chickens weren’t on my to-see list but as we drove out of the airport, there they were, freely roaming the roadsides. During the next week, we met handsome, colourful, confident chickens everywhere – from beach to mountaintops, from suburbs to national parks. Why so many? Who owns them? Who eats them? Their story led us into the much bigger picture of island colonization.

The Hawaiian archipelago was born of fire. As the great Pacific tectonic plate drifted northwest over a ‘hot spot’ or convection plume in Earth’s molten magma, successive volcanoes erupted out of the sea and formed a long chain of islands. The oldest ones, up to 60 million years old, have eroded away and mostly disappeared under the sea. The youngest island, Hawai’i, is currently over the hot spot and still has active volcanoes. Further northwest, Kaua’i is 5 million years old.

The cooling volcanoes were colonized by wandering birds and insects, by seeds borne on wind or ocean currents or in birds’ bellies, and by small animals clinging to rafts of floating vegetation. Lush vegetation grew up, but who would eat it? On islands worldwide, this has played out in different ways. In Galapagos and Aldabra tortoises became the herbivores. Mauritius had giant pigeons, the dodo. Madagascar had lemurs, and New Zealand had 11 giant flightless birds called ‘moa‘, a Polynesian word for any fowl.

Two people looking at a sunken cave site on Kauai

Jeannette and docent in Makauwahi sinkhole, Kaua’i

Drawing of 6 extinct and 1 extant goose species from Hawaii.

Moa-nalo; only the nene (far right) survives today. From a drawing displayed at Makauwahi.

The largest herbivores to reach the Hawaiian islands were ducks, 3.6 million years ago. Lacking predators, they evolved into several flightless forms, some as big as domestic geese. Later, ancestors of today’s nene goose joined them. They became abundant, eating ferns and grass and tree seedlings. At Makauwahi archaeological site, which preserves 10,000 years of remains, we learned that in 300-800 CE, the first Polynesians encountered 7 species of these “moa-nalo” (lost fowls).  Unafraid of man, they were soon exterminated. The people brought pigs, which also ate moa-nalo, and chickens, which quickly filled their vacant ecological niche. Moa-nalo were forgotten until archaeologists discovered their bones in the 1980’s.

Enter the chicken! The Asian red jungle fowl, domesticated 8-10,000 years ago, is hardy, tough and eats anything. It is only vulnerable when it nests, on the ground. In all the other Hawaiian islands, sugar farmers introduced mongooses to control the (introduced) rats. But rats are nocturnal, so the diurnal mongooses attacked birds instead, especially ground-nesters; only Kaua’i’s chickens are safe from that threat.

Today the “wild” Kaua’i chickens in parks and reserves are protected. You can harvest chickens that enter your property, but they may be tough. Islanders say: “To cook the moa, boil it in water, with spices and a rock. When the rock is soft, the moa is ready!”