All things considered, Álvar Núñez Cabeza de Vaca was a hopeless conquistador. Not for him the gore-drenched glories of Cortés or Pizarro. His first expedition to the New World ended in shipwreck and enslavement, his second in deportation and disgrace. Yet if Cabeza de Vaca achieved much less militarily than other Spaniards in the New World, he nonetheless cries out to be remembered. During a long and stormy career, he became entranced with the native cultures he encountered, and has been described as a kind of proto-anthropologist. More than that, this fighter and adventurer would eventually find ways to sympathise with societies wildly different from his own, and maybe even nudge Europeans towards modern ideas of common human dignity.

His upbringing would hint at none of this. He was born around 1490, on the arid Andalusian plain, in a land drunk on Reconquista. Granada, the last Muslim stronghold in Spain, would fall in 1492. That same year, the country’s Jews were expelled by royal decree. Cabeza de Vaca was weaned on family tales of brawny Christian zeal. His grandfather had conquered Gran Canaria, killing and enslaving as he went. An older ancestor, a shepherd, had made a mark as well. In the thirteenth century, he had supposedly marked an unguarded mountain pass with a cow skull, helping Christian forces vanquish a rival Moorish army. Apocryphal or not, the story presumably mattered to young Álvar: Cabeza de Vaca means ‘Cow’s Head’ in Spanish.

Together with his own education — he spent his early twenties fighting the French in Italy — there’s little reason to imagine Cabeza de Vaca as much more than a brawler. As one popular contemporary song vividly evoked, sixteenth-century Europe was bloated with such men, armed with lances, the small round shields known as bucklers, and ‘on a spree’ to buy shoes with their loot. In 1527, however, everything would change. That year, Cabeza de Vaca joined a mission to colonise Florida – an expedition that crumbled from the start. Desertions ravaged the conquistadors before they even reached the American mainland, while many more were lost through shipwrecks and raids by local tribes. By the start of 1529, Cabeza de Vaca and a few other survivors were essentially slaves, living in filth among various bands of Indigenous Peoples in Southern Texas. ‘I could not bear the kind of life I had with them,’ he would later say of one clan, adding that his diet consisted of roots he pulled from the ground.

We know these torments thanks to La Relación, Cabeza de Vaca’s account of his adventures. Across 109 pages, he tells of his dramatic escape from captivity in 1534, and the heroic trek that followed. By the time he reached the safety of Mexico City in the summer of 1536 — a city recently snatched from the Aztecs and renamed by Hernán Cortés — the bruiser from Andalusia had been lost for nearly a decade. Along the way, Cabeza de Vaca and a trio of other survivors were the first outsiders ever to see the American Southwest, their odyssey ultimately carrying them for thousands of miles from the Atlantic to Texas, from Florida marshlands to the Rio Grande.

That would be reason enough to remember Cabeza de Vaca. Yet La Relación transcends mere geographical curiosity. With a sharp eye and a passion for detail, the author recalls the places he saw and the people he met, for the first time setting down in ink a world that had existed unknown to Europeans for hundreds, even thousands of years. Some later experts have characterised his account in quasi-anthropological terms, a plausible claim given just how much physical evidence you can still find of Cabeza de Vaca’s observations. Visit the deserts of Northern Mexico, for example, and you’ll see the same breed of spindly pine tree. The nearby Indigenous Peoples, for their part, still made black paint from a mineral called pyrolusite into modern times — just as Cabeza de Vaca recounted. The fact that some of the tribes encountered by Cabeza de Vaca have since become extinct only makes La Relación even more valuable, as historians fight to revive a vanished world in the American West.

Apart from the broad sweep of his journey, Cabeza de Vaca was just as fascinated in specific cultural habits. His variety here is bewildering. On one page, he describes a group whose warriors camouflaged themselves in brushwood, all the better to ambush their enemies. On another, he meets people who found religious significance in hollow gourds filled with pebbles. A third culture — which Cabeza de Vaca dubs the ‘Cow People’ — hunted buffalo, with women dressing in in deer hides. The narrator was particularly curious about native cooking, explaining how the communities he met lived on everything from cornmeal to fish to mesquite flour ground with a pole ‘as thick as a leg’ and nine feet long. At one point, Cabeza de Vaca is fed ‘prickly pears and spiders and worms’ by a group of women. Though the women were hungry themselves, he stressed that ‘they would not eat anything’ unless offered it directly.

As this last comment implies, Cabeza de Vaca and his friends often relied on the generosity of strangers to survive. In part, this dynamic had a strong religious dimension. A devout Catholic, he succeeded in introducing a measure of Christianity to the people he met, many of whom came to see him as a mystic and healer. Indeed, Cabeza de Vaca’s medical knowledge may also explain his friendly reception. Towards the end of his trip, he was accompanied by crowds of supporters, the Indigenous Peoples potentially drawn to his skill in fixing wounds. Beyond these remedies for the body and soul, however, you get the sense that Cabeza de Vaca was welcomed on purely humanistic grounds, as a guest to be pitied and helped. In one of the most startling episodes of La Relación, he describes being found, shipwrecked and desperate, by a group of tribespeople near what is now Galveston. ‘They felt such great pain and pity at seeing us in such a state,’ Cabeza de Vaca wrote later, ‘that they all began to cry so loudly and sincerely that they could be heard from afar.’

These heartfelt meetings forced Cabeza de Vaca to reconsider his self-image. No longer a brutal conquistador in the mould of his grandfather, he came, in the words of one modern scholar, to see the people he encountered as ‘human beings’ worthy of respect. Certainly, this transformation can be traced throughout his book. Early in his ordeal, for instance, Cabeza de Vaca writes that he saw the people he encountered as ‘crude and untutored.’ But the more he explored this alien land, the more he softened. Dazzled by the military prowess of one tribe, he compared them favourably to the troops he’d seen in Italy. As so often, food was another area that impressed him. ‘Since their way of cooking them is so novel,’ he said of one community’s bean and squash meal, ‘I want to tell about it here, so that people may see and know how diverse and strange human ingenuity and industriousness are.’

By the end of La Relación, Cabeza de Vaca was defending Indigenous Americans from rapacious Spanish slavers — and continued to do so for the rest of his life. After returning to Spain, he was dispatched on a second colonising mission, this time to Paraguay. Once there, Cabeza de Vaca tried to protect the Guaraní people he found, to the extent that he was soon arrested on trumped-up charges by his fellow settlers. Shipped back to Europe in chains, he spent years trying to clear his name, dying around 1559. Not that Cabeza de Vaca’s story of compassion ends there. For one thing, it would influence Bartolomé de las Casas, a Dominican friar and energetic defender of Indigenous American rights. De las Casas probably read La Relación and used it to shape his philosophy of basic human worth. ‘All the peoples of the world are men,’ is how he famously phrased it, with one recent paper treating both him and Cabeza de Vaca as forerunners of later international law. Beyond that, Cabeza de Vaca enjoyed a happy afterlife in the lands he explored. As the first Spaniard to traverse the region, he would become an icon of Chicano culture in the American Southwest.

Even so, it’d be wrong to paint Cabeza de Vaca as a modern cultural relativist. Despite being a victim of the practice, for instance, he was apparently as comfortable as most sixteenth-century Europeans with the concept of slavery. One of Cabeza de Vaca’s fellow survivors, in fact, was a man called Estevanico, tersely described on the last page of La Relación as a ‘black Arab’ from Morocco. The book doesn’t say so, but other sources make clear that Estevanico was himself a slave, owned by another of Cabeza de Vaca’s companions and forced back into servitude once he reached Mexico City. Though he later regretted this position, for his part, de las Casas tellingly urged gentleness towards Indigenous Americans while simultaneously arguing that imported African slaves should do their work instead.

The broader context of Cabeza de Vaca’s wanderings can make for uncomfortable reading, too. He may not have meant it, but he likely introduced European diseases to some of the peoples he met, hastening their destruction even as he recorded their lives for posterity. At the same time, some have argued that Cabeza de Vaca emphasised his tale of brotherly love to win favour back in Spain — all the better to colonise the Indians if they’ll accept Christ without a fight. Then there’s the question of what would have happened had Cabeza de Vaca simply been luckier. He was, after all, clearly not against imperialism in general. And given so much of his empathy was crafted by circumstance, the story of a wretched man forced to grasp the humanity around him, you have to wonder if he would have had the same insights in different circumstances.

To put it another way, and especially given the grim epic of Spanish conquest from Mexico to Peru, would a Cabeza de Vaca armed with lance and buckler have shown the same generosity of spirit he eventually did? Perhaps not. But history has left us with this version of Cabeza de Vaca, flailing and flawed, a Cabeza de Vaca raised in the killing grounds of Europe, but a man who ended up sacrificing his own freedom for the ‘strange human ingenuity’ he so came to admire. That a sixteenth-century brawler could come to such thoughtful conclusions is uncommon indeed.