Origins: How the Earth Shaped Human History, by Professor Lewis Dartnell

In Sky this Month, Mike Meynell provided some interesting observational challenges for the next month, including the well-positioned M51 (Whirlpool) and M81/82 (Bodes/Cigar), La Superba a carbon red giant, and closer to home, noctilucent clouds. 

Professor Lewis Dartnell then treated Flamsteed to a unique perspective on human history based on his latest bestseller of the same title. For the first time this season, we were not looking outwards into the cosmos, but rather at our own modest rock, Earth. Or maybe not so modest. Lewis provided some fascinating examples of how specific histories have been influenced by timeless geological and atmospheric processes.

Professor Lewis Dartnell at the start of his talk to the Flamsteed. Picture by Mike Meynell.

The Rift Valley maketh Man

Homo Sapiens was forged in the Rift Valley, the only land mass on the equator which had the perfect conditions for Apes to migrate from wet, arboreal environments out into grasslands. Movement of tectonic plates created a large fracture in East Africa, and in consequence a dry savanna valley protected by mountains. Milankovitch cycles which modify earth's solar orbit on timescales of tens of thousands of years, provided variable tweaks in the climate. In the Rift Valley this led to changes in stored water abundance through the expansion and contraction of numerous lakes. Lewis' thesis is that a few hundred thousand years ago, these environmental challenges acted as a catalyst to brain size and increased intelligence. The same cycles also created the ice ages that in turn provided land bridges for Homo Sapeins to spread throughout all the major global land masses.

Explaining the trade routes. Picture by Paul May.

Trade Winds favour the West

Differential heating at different latitudes of the Earth, combined with rotational forces has created a stable pattern of winds operating in different directions depending on latitude. First the Portuguese, then the Spanish and the Dutch and finally the British found ways to exploit these patterns to great trading and hence financial advantage. Many current cities were developed as ports based on these patterns and hence despite the technological surpassing of 'sail', many of these trading links are relevant today. Lewis' book contains many other examples of shaped histories, and the subsequent sell-out at the book signing was testament to the success of the lecture. Thank you Lewis!

Another big Flamsteed audience for our May 2025 lecture. Picture by Bobby Manoo.

Personal Afterthoughts

To what extent has our history been not only shaped but determined by such fundamental physical forces? If so, are the conditions that created Homo Sapiens and led to our increased technological capability almost unique? And in that case, are the conditions for technologically advanced cultures on other planets so extremely unlikely that we may be, if not alone, very unusual? Perhaps a solution to the Fermi Paradox - a topic of one of our lectures for next season!

Pictures from the evening (by Bobby Manoo, Paul May and Mike Meynell):