The Poppies of Terra #63 - What Makes Us Human

A formative book for me in high school was Shadows of Forgotten Ancestors (1992) by Ann Druyan and Carl Sagan. In a series of beautifully written essays, Druyan and Sagan contextualize modern humans as products of a vast evolutionary process, sharing deep biological and behavioral roots with other species (e.g., chimpanzees, gorillas, bonobos, and orangutans), while also being uniquely shaped by cultural and intellectual advancements such as language, tool-making, art, and scientific inquiry. 

I remember being particularly struck by the penultimate piece, “The Animal Within,” in which Druyan and Sagan argued that humans differ from other species in degree but not in kind. They splendidly illustrate a continuity of traits like intelligence, emotion, and social behavior across species, emphasizing that human capacities are extensions of those found in other animals, particularly primates, rather than being fundamentally different. How remarkable, I thought–and still do.

Over the ensuing decades, dozens of best-selling general audience science books have taken up the mantle of Shadows’ themes, often going deeper on particular topics and leveraging the latest discoveries. Frans de Waal, for instance, a well-known biologist and primatologist, has recently published two memorable volumes along these lines. Are We Smart Enough to Know How Smart Animals Are? (2016) challenges human exceptionalism by exploiting and celebrating the depth and breadth of animal intelligence, while Mama’s Last Hug: Animal Emotions and What They Tell Us About Ourselves (2019) investigates animals’ rich emotional lives, again highlighting kinships with our own human capacity for feeling. 

A number of our ancestral cousins, such as Neanderthals, have long captivated the imagination of science fiction writers. From H.G. Wells’ “The Grisly Folk” (1921) to Isaac Asimov’s “The Ugly Little Boy” (1958) to Robert J. Sawyer’s Neanderthal Parallax trilogy (2002-2003) to James Bradley’s recent Ghost Species (2020), along with many others, our long extinct evolutionary brethren have been speculatively resurrected time and again. Outside of science fiction, the rousing success of Jean M. Auel’s The Clan of the Cave Bear (1980) started a whole new publishing category of prehistoric fiction.

A few years ago Robert Silverberg, who expanded Asimov’s famous story into a novel in 1992, penned an essay on Neanderthals in which he discusses Rebecca Wragg Sykes’ Kindred: Neanderthal Life, Love, Death and Art (2020), a magnificent synthesis of recent findings that shed Neanderthals in a new light: a sophisticated, adaptable, and culturally complex parallel human species, rather than the stereotypically primitive beast-folk of pop culture.

Before Sykes, Clive Finlayson argued in The Humans Who Went Extinct: Why Neanderthals Died Out and We Survived (2009) that climate change and resource competition outpaced Neanderthals’ ability to adjust, while our adaptive prowess and skills with innovation kept us afloat.

These are haunting and enduring questions. Why did several early species of humans die out, while we persevered? How can we cup a hand behind the ears of our science and capture their long-lost reverberations?

Tackling these mysteries, and in a direct lineage of Druyan and Sagan’s book, now comes Human (2025; available in the US on PBS Nova starting September 18th), a stunning new BBC documentary series. Through five thought-provoking and deeply affecting episodes—“The First of Us,” “Into the Unknown,” “Last Humans Standing,” “Discovering the Americas,” and “A Great Gamble”—this series voyages across the globe and roams through immensities of time to follow the complex, often unbelievable trail of our evolutionary origins.

Ella Al-Shamahi, a British paleoanthropologist, evolutionary biologist, explorer, author (The Handshake: A Gripping History, 2021), and science communicator, makes for a superb tour guide. Unlike many other recent science docus, which skirt histrionics in their perceived need to retain the attention of a hypothetically flighty audience, Human has confidence in both its material and our intelligence to appreciate it.

By turns celebratory, contemplative, and even elegiac, the series takes its time–and in so doing, recaptures ours. Excellent production values, including a sweeping but layered score by Paul Saunderson, make this a first-rate outing.

Al-Shamahi’s early observation that our story is “what happened in the 99% of our history before the invention of writing, when our story wasn’t written in books, but was written in our bones and DNA,” gave me chills. Most of everything our species, and those closest to it, has ever experienced, is gone. Each small glimmer of understanding about these vast stretches of undocumented time is therefore precious. 

Among Human’s fascinating revelations: 

• Homo floresiensis (very early, hobbit-like humans) lived for potentially over 700,000 years, surpassing our species’ current existence

• Neanderthals thrived for around 400,000 years before their eventual decline and absorption

• Every individual outside Sub-Saharan Africa carries about 2% Neanderthal DNA, a genetic echo of ancient interbreeding. Neanderthal DNA present in all living humans could account for approximately two-thirds of the entire Neanderthal genome

• Denisovan DNA has also been found in Homo sapiens populations. In some regions, such as the Philippines, this contribution can be as high as 6%

• Homo sapiens first appeared over 300,000 years ago, making us a third older than previously believed

• Around 70,000 years ago, Homo sapiens innovated complex projectile weapons like the bow and arrow

• Fossilized human footprints, including a parent carrying a child, dated to possibly 21,000 to 23,000 years ago, push back the timeline for human arrival in the Americas

As Al-Shamahi trots across the globe, from Morocco to Ethiopia, from Botswana to Flores, Indonesia, from Romania to Southern France and Northern Spain, from New Mexico to Egypt, among other places, she consistently stops to ponder how the findings shared with her by experts illuminate what helps to define us. 

We learn, for instance, that anatomically modern humans, like Herto 1, possessed physical characteristics overwhelmingly similar to ours, including rounded, or globular, skulls, and that this globularization may reflect a significant change in brain organization, leading to enhanced cognition and coordination. Then, too, Homo sapiens children grew up more slowly than the offspring of earlier human species, providing an extended period for learning and complex brain development. Ritualistic behaviors suggest that we gained the ability to imagine things beyond the tangible, and learned to see the world not just as it was, but as it could be, a tremendous boon for technological advancement. Our cumulative culture shepherded knowledge across generations, making us exponentially smarter. We discovered the incredible power of cooperation. We are the only humans known to have mastered seafaring technology, and were the first to domesticate other living things, beginning with wolves (leading to dogs) around 40,000 years ago in Siberia, providing an advantage in hunting and protection. And so on and so forth, in a dizzying array of breakthroughs, setbacks, and recoveries.

From small bands of nomadic hunter-gatherers to a dominant force reshaping the planet itself, it’s a lot to take in. And indeed, the documentary isn’t simply an exercise in triumphalism. Quite rightly, Al-Shamahi poses a troubling thought. “Those same things that make us so remarkable,” she muses, “seem to be damning to those around us.” In The Epic of Gilgamesh, one of our oldest stories, the hero’s extraordinary strength and divine heritage make him both capable of great deeds and destructively tyrannical to his own people, necessitating the gods’ creation of Enkidu to balance his overwhelming power. Our history is littered with the remnants of our inner, hereditary Gilgamesh. Deftly chronicling and perspectivizing our past, Human becomes a necessary Enkidu for our age.