Paranthropus aethiopicus
Paranthropus aethiopicus is said to be one of the most controversial fossils ever found

My phone shows the time as 1am. That means 2 hours I've spent distracted to insomnia by the mating dance of an amorous mosquito couple overhead, just above my bed net. The strengthening and softening of their high pitched buzzing as each gets nearer and farther gives the impression of WW2 fighter planes engaged in a dogfight and the room seems to echo with each duck, dodge and dive. If I can't sleep, I might as well write. At least the mosquitos in Nairobi don't carry malaria.

My day was spent with a friend at Kenya's National Museum. The museum contains skeletons of lions, elephants, giraffes and other famous animals of Kenya, artefacts from Kenya's 42 tribes and a history of the country's colonial times. This is exactly what a visitor would expect of a national museum. But much less expected and little trumpeted is a truly remarkable collection towards the back of the museum: the world's finest and oldest collection of early humanoid fossils, our ancestors.

The collection is in a room just ten metres by ten with each item given a short explanation on an accompanying poster. The information, however, is unimportant – I was not there for an abridged Wikipedia article. What matters in this collection is the very experience of it.

On entering the gallery room you are immediately faced with the skull of proconsul, an ancestor of both humans and apes, once thought to be the Missing Link. This skull, the only complete proconsul ever found, is 18 million years old. 18 million years: an incomprehensible length of time but just about enough for evolution to take its course and produce the larger skull and longer legs of the visitors gaping at it in this small room.

A little further, to the left, is the "Black Skull". It has two possible Latin names, Paranthropus aethiopicus and Australopithecus aethiopicus, the ambiguity depending on which scientist you ask as the Black Skull is, according to the information beside it, "one of the most controversial fossils ever found". It hasn't quite incited riots but it has divided researchers over its place in our family tree, due to the complications of parallel evolution, in which species can independently evolve similar characteristics. The Black Skull, so called because of its dark colour from being buried in manganese, is 2.5 million years old and a further step up the ladder towards humanity.

1.9 million years old and nested in the opposite corner is Homo Rudolfensis, the oldest fossil found to have a brain size large enough to compare with modern humans. It sits beside a skull of Homo Erectus, the first hominid to use fire, the Large Hadron Collider of its day. This skull is 1.75 million years old, the most complete of its type ever found, and once held the brain of what could be considered one of the first scientists.

In following this path around the gallery, visitors are circling, almost ritualistically, around a glass covered table in the centre. The glass showcases the most important fossil in the world and, at 1.6 million years old, the baby in the room. This is the Turkana Boy, named after the region of Kenya in which he, and most of the fossils in the room, were found. He died aged eight and, with a skull and almost complete body of 108 bones, he is the most complete skeleton of an early hominid ever found. He was a tall eight-year-old at 5"3', which would mean he could have grown as tall as 6"1' had he survived to adulthood, suggesting Homo Erectus was much taller than theories had expected. Were you to meet this boy face to face by the shores of Lake Turkana, you would see someone not dissimilar to a modern child.

It is a strange and humbling experience to stand as a Homo Sapiens in this gallery, surrounded by ancestors. This is increased by the low key setting, due in part to pressure on the museum from creationist Christians. The result is a rarity for a modern museum; a gallery that leaves much of the thinking to the visitor. It is just as possible to pass through the gallery unaffected and unmoved as to feel anything. Unconcerned by the threat the gallery poses to the religious, the humanist visitor is left simply with a powerful sense of time, the realisation that we humans are standing on a great many shoulders.

The creationist fear of such an exhibition is easy to understand. To be faced with the skull of an ape-like ancestor is to be faced with the bare truth that however much we may advance, humans remain animals. For many, this idea is a dangerous one. But for the humanist, it must be embraced. Embraced as truth. Ever since Galileo the human animal has been confronting itself with the notion that we are not the centre of this universe, indeed the universe is quite indifferent to its observers.

The Kenyan National Museum shows this in its starkest form. Hundreds of thousands of generations have passed before us and hundreds of thousands will pass afterwards. One day we too could find ourselves fossilised and on display in a museum for the next form of hominid, a passing curiosity for tourists. The desire to preserve ourselves, the insistence on the possibility of eternal life and a divine plan, these are shown up as in vain. All we can know, all we can live for, whether the mosquito animals above me in their Spitfire-esque seduction or the human animals asleep in the room next door, is the present. All the future offers is a spot in a museum next to a carefully excavated bottle of WKD.