The coast-line on Danakil where both the Australopithecus and Paranthropus genus speciated, would have been different from the surrounding regions in that it was an open landscape, where the field of vision stretched across the Sea of Afar, with the mountains that made up most of Danakil as a frame to the north, north east, and south.

Australopithecus would in that sense have been adapted for an open grasslands ecosystem, as “beach apes” that foraged shell fish from the coast line on south western Danakil. As the pliocene flood basalts ended the isolation of this “galapagos of the great apes”, the Australpithecines settled by lake Turkana, some 1000 km to the south-west, and began to speciate into Homo.

The trail of memetic cognition, aridification and wildebeests

In the absence of an open grasslands landscape, the Australopithecus, a memetic species from their loss of olfaction at 3.86 million years^[1] before the present, as well as adaptations for volitional control of breathing^[2], with attentional modulation as a byproduct, had the capability to manipulate their environment, to make the ecology at lake Turkana adapt to them.

The earliest fossil evidence for the presence of the genus Connochaetes is C. gentryi (Harris 1991) from the Upper Lomekwi Member of the Nachukui Formation, West of Lake Turkana dating to between 3.0 to 2.5 million years ago (Harris et al. 1988; Harris 1991).

The evolution and dispersal of the typically African alcelaphine bovids and the dispersal and speciation of taxa of non-African origin, such as the zebras, are linked to the aridification of the southwest, the northeast and the north of Africa, centres of endemism for arid and semi-arid adapted forms.

Volcanoes and fire, cooking, and aridification

Vast lava flows may have provided humans with access to heat and fire for cooking their food millions of years ago. The same tectonic events that forced Australopithecus away from Danakil, also opened up conditions for the continued evolution of the human lineage, with fire being widely accessible from volcanoes at lake Turkana.

References

A comparison of the human and chimpanzee olfactory receptor gene repertoires (2005)

Breathing above the brainstem: Volitional control and attentional modulation in humans (2017)

The remote lake that tells the story of humanity’s birth (2015)

Turkana and the Dawn of Man (2016)

Volcanoes Sparked an Explosion in Human Intelligence, Researcher Argues (2015)

Notes

• The mechanism of Nothobranchius diversification was allopatric and driven by geographic isolation. We propose a scenario where diversification of Nothobranchius started in rough coincidence with aridification of East Africa, establishment of grassland habitats and the appearance of the typical African bovid fauna of the savannah.

• Savannas are subject to regular wildfires and the ecosystem appears to be the result of human use of fire. For example, Native Americans created the Pre-Columbian savannas of North America by periodically burning where fire-resistant plants were the dominant species
  https://en.wikipedia.org/wiki/Savanna#Changes_in_fire_management

• Man-made fire has been such a universal factor in savanna ecosystems for so long that it is often impossible to determine how much of the African savanna is the result of human impact. Until recently, it was generally accepted by ecologists that, in the absence of expert supervision, human influence in the form of burning, cutting, stock grazing, and cultivation has almost invariably been in the direction of downgrading the environment from complex to simple communities, turning forest into scrub or savanna, moist savanna into arid savanna, and arid savanna into subdesert scrub. In other words, human influence has been considered to degrade habitats. Some ecologists have gone so far as to argue that practically all African grasslands have been created and maintained by humans, primarly through fire.

• Fossilized traces of the horse, which was named Eurygnathohippus woldegabrieli, were uncovered in the archaeologically rich sites of Aramis and Gona in Ethiopia's Middle Awash valley. The region is famed for bearing the world's longest and most continuous record of human evolution. The extinct horse in this study would have actually been alive at the same time the 4.4-million-year-old human ancestor Ardipithecus ramidus, or "Ardi," walked the region. [Beasts of Burden: Amazing Horse Photos]
  The species was estimated to be about the size of a small zebra, and had three-toed hooves.[1] Tooth wear patterns and analyses of bone composition indicate that E. woldegabrieli grazed on grasses similar to the coarse C4 diet of modern zebras or wildebeests.[2] Compared to ancestral Eurygnathohippus horses of six to ten million years ago such as the late Miocene E. feibeli, which lived and ate in forests, E. woldegabrieli's teeth were taller and more worn, and its longer and thinner leg bones suggest that it was well adapted for running.[2] The medial Pliocene species E. hasumense, a more advanced horse from 3.5 million years ago and forward, is both taller and has a longer nose than E. woldegabrieli, a further advanced adaptation toward living in open grasslands.[1][2]