SF novella from 90-10's in which aliens archaeologists look into human history on earth

Question

I'm looking for the title of a story about aliens which study human history.

The story is set in the distant future, where humans conquered the universe and were extinguished.

Few aliens came to Earth to get to know human history. One alien is capable of seeing history by touching things. So it tells few short stories from different human eras: prehistorical, medieval, modern and future.

All stories happend in Africa, but in different time.

First story is about early humans. Namely, aliens first visited the earth, were caught and killed by early humans.

Second story is about slave trade. The slave kills its master and became the slave trader(?)

The third story is about revolution in Africa and killing colonizers.

The forth story is about illegal dumping of radioactive waste.

The fifth is about people leaving earth because of high radioactivity.

Answer 1

Seven Views of Olduvai Gorge by Mike Resnick

“Seven Views of Olduvai Gorge” is a 1994 science fiction novella by Mike Resnick. It is set in the far future when a group of anthropological aliens are studying the long and brutal empire of mankind.

Many centuries after the Empire of Man came tumbling down, a group of anthropologist aliens are visiting the birthplace of mankind – Olduvai Gorge in Africa. Each member of the group has one particular scientific specialty, but the narrator – know only as He Who Views – has an extra special function – the ability to morph with an artifact and re-live its story. The group finds seven different objects and consequently learn the fascinating details of each one’s existence. Through He Who Views eyes we are treated to several detailed stories spanning the age of Mankind. We learn about the aliens who visited Earth when man was little more than a violent ape; Mtepwa the slave boy who rose to become head of a great and terrible trading empire; Chelmswood, a guard in the rough shod Leakey museum; Kevin, the Maasai guide leading tourists on big game viewing safaris; Joseph, the man who accepted bribes for a terrible cover up that haunts his soul; and Thomas, the proud man who does not want to leave the land of his fore-fathers for a new planet.

Answer 2

Could this be Birthright: The Book of Man, by Mike Resnick?

Birthright spans a timeline of nearly 17 millennia, beginning at a very early stage of expansion from Earth and ending with the death of the last humans. In between, it chronicles a slow but (despite some set-backs) steady conquest of the entire galaxy - inhabited by thousands of sentient alien races, which are overpowered and oppressed using whatever tool it takes: economic pressure, diplomatic finesse, or simple military power.

Not all chapters deal with humanity's treatment of aliens; some also cover the "internal" politics that result in a development of the growing human empire from a democracy to a monarchy. But the biggest theme is undeniably the search for the elusive quality that allows humanity to overcome all opposition and manage the unique feat of conquering the entire galaxy. It is never clearly defined but manifests perhaps most succinctly when it also results in the failure of an attempt to cross the void between galaxies.

Then, after there is no more room for conquest, the only way left is down: internal struggles as well as deep-seated resentment of aliens result in a decline of human power that takes nearly as long as the rise, but is described far less extensively. Somehow, despite whatever enabled humans to achieve total power, they were unable to keep it.

Displaying a particular brand of irony, one of the chapters reveals the "literary genre of fiction" as another of humanity's peculiarities, not shared by any alien race.