A hundred years after his death Alfred Russel Wallace (1823-1913) is usually remembered, if at all, as the other person who alongside Darwin discovered evolution’s mechanism Natural Selection. The truth is far more significant and is fascinatingly tied into the first understanding of biodiversity and the emergence of environmentalism.
That fateful letter which Darwin received from Wallace which culminated in their ideas being co-presented at the Linnaean Society in 1858 did not appear out of nowhere. As a young man Wallace had avidly read Darwin’s Beagle Journal of his circumnavigation around the globe with Captain Fitzroy. Twenty years later, Wallace was already a seasoned collector having spent years in the Amazon. On his return to Britain he had made contact with Darwin and when he traveled to the Malaysian Archipelago (Indonesia), they corresponded via the months-long mail-ship journeys through the Atlantic around the Cape and across the Indian Ocean. Some of the letters survive to this day recording how the two were discussing how species changed, and how this happened over time and geography.
Darwin’s own interest in nature, begun more than 30 years earlier, had come to focus on one particularly big question – what was the origin of species? We must understand what this question meant to him – he was asking how do you explain the extraordinary variety in nature; that is, how do you account for biodiversity? Why weren’t there fewer, simpler forms? Both he and Wallace were to come to the same conclusion – that it resulted from an evolutionary process over time driven by the mechanism Darwin called Natural Selection. But it is important to note that Darwin’s question had not pre-supposed this evolutionary outcome, he hadn’t set out to identify an origin of life, but an explanation for its great natural variety.
Darwin had begun with an essentially Christian outlook that presupposed the fixity of species and that the benefits of nature were a divine providence to Man. On the Beagle Voyage Darwin began to be persuaded by the geological evidence he saw that the earth was immensely older than had been previously conceived. At the same time we discover in his journal that his presumptions about the fixity of species and of providence for people were being challenged too.
As he walked around the Bay of Islands on North Island New Zealand he was impressed by both the massive Kauri Forest and by the vast tracts of bracken fern, and he writes…
‘The sight of so much fern impresses the mind with an idea of sterility: this, however, is not correct; for wherever the fern grows thick and breast-high, the land by tillage becomes productive. Some of the residents think that all this extensive open country originally was covered with forests, and that it has been cleared by fire. It is said, that by digging in the barest spots, lumps of the kind of resin which flows from the kauri pine are frequently found. The natives had an evident motive in clearing the country; for the fern, formerly a staple article of food, flourishes only in the open cleared tracks. The almost entire absence of associated grasses, which forms so remarkable a feature in the vegetation of this island, may perhaps be accounted for by the land having been aboriginally covered with forest-trees.’
Darwin is very clearly highlighting the massive human induced (anthropogenic) impact on the environment, even by aboriginal peoples (with the assistance of fire). Incidentally some 70 years before Darwin’s visit, the naturalists on Captain Cook’s 1st Pacific voyage had witnessed from the deck of HMS Endeavour ‘great smokes’ on the hillsides of New Zealand and suggested this was some form of agricultural burning by the Maori.
Even more significantly Darwin records the impact of introduced alien species noting…
‘It is said that the common Norway rat, in the short space of two years, annihilated in this northern end of the island, the New Zealand species. In many places I noticed several sorts of weeds, which, like the rats, I was forced to own as countrymen. A leek has overrun whole districts, and will prove very troublesome, but it was imported as a favour by a French vessel. The common dock is also widely disseminated, and will, I fear, for ever remain a proof of the rascality of an Englishman, who sold the seeds for those of the tobacco plant.’
Then on the return journey through the South Atlantic the Beagle visited the island of St Helena, the British Overseas Territory. There he examined the remains of shells at a number of locations on the island, finding they belonged to eight different species of land snails of which he wrote…
‘It is remarkable that none of them are now found living. Their extinction has probably been caused by the entire destruction of the woods, and the consequent loss of food and shelter, which occurred during the early part of the last century… So late as the year 1716 there were many trees, but in 1724 the old trees had mostly fallen; and as goats and hogs had been suffered to range about, all the young trees had been killed… The extent of surface, probably covered by wood at a former period, is estimated at no less than two thousand acres; at the present day scarcely a single tree can be found there. It is also said that in 1709 there were quantities of dead trees in Sandy Bay; this place is now so utterly desert, that nothing but so well attested an account could have made me believe that they could ever have grown there… There can be little doubt that this great change in the vegetation affected not only the land-shells, causing eight species to become extinct, but likewise a multitude of insects.’
However, while the young Darwin was noting these ‘man and biosphere interactions’ in his later work and private letters there is barely an inference of what we could interpret as a call for conservation or environmental action. In 1874, late in this life, Darwin did sign a petition organised by Albert Günther, Keeper of Zoology and the Natural History Museum. It urged the Governor of Mauritius to protect the Giant tortoises on the nearby Indian Ocean island of Aldabra (part of the Seychelles). The tortoises were threatened by logging activity on the small island (the Mauritian species of Giant Tortoise had already been driven to extinction alongside it’s famous Dodo). This petition led to the Governor effectively commissioning one of the first ever captive breeding programmes; bringing tortoises off Aldabra to the Governor’s mansion on Mauritius where they were protected in the substantial grounds gardens. However, this is an exception, it wasn’t initiated by Darwin and it was primarily a call for the preservation of a ‘scientific curiosity’.
Issues such as animal welfare had begun to rise in Europe prior to Darwin’s Beagle voyage (the Society for the Prevention of Cruelty to Animals was formed in London in 1824). There had been awareness of the decline of the Great Auks across the North Atlantic for a considerable time. In fact an early environmental law banning Auks being hunted for eggs and feathers with the penalty of public flogging had been passed in St John in Labrador half a century earlier in 1775. Significantly in 1840, in the intervening years between Darwin’s Beagle voyage and Wallace’s travels the last Great Auk in the British Isles was killed on St Kilda. Over these intervening decades the European Empires were increasingly impacting on the environment as they fed on the resources of the colonies. As Wallace, following the journal writing tradition of previous naturalists, wrote his fabulous work The Malay Archipelago he was conscious of this impact, his concern is famously captured in his account of the glorious King Bird of Paradise.
‘I thought of the long ages of the past, during which the successive generations of this little creature had run their course — year by year being born, and living and dying amid these dark and gloomy woods, with no intelligent eye to gaze upon their loveliness; to all appearance such a wanton waste of beauty. Such ideas excite a feeling of melancholy. It seems sad, that on the one hand such exquisite creatures should live out their lives and exhibit their charms only in these wild inhospitable regions, doomed for ages yet to come to hopeless barbarism; while on the other hand, should civilized man ever reach these distant lands, and bring moral, intellectual, and physical light into the recesses of these virgin forests, we may be sure that he will so disturb the nicely-balanced relations of organic and inorganic nature as to cause the disappearance, and finally the extinction, of these very beings whose wonderful structure and beauty he alone is fitted to appreciate and enjoy. This consideration must surely tell us that all living things were not made for man.’
Wallace like Darwin, was seeking answers to big questions, and in Wallace’s case, after he returned to Britain two of his many books focused particularly on what today we call biogeography; the relationship between physical geography and species boundaries. In these books we also see a very different voice emerging on the impact of people on nature. In his book Island Life (1881), Wallace picks up from where Darwin left off, with the human influenced degradation of St Helena.
‘…yet the general aspect of the island is now so barren and forbidding that some persons find it difficult to believe that it was once all green and fertile. The cause of this change is, however, very easily explained. The rich soil formed by decomposed volcanic rock and vegetable deposits could only be retained on the steep slopes so long as it was protected by the vegetation to which it in great part owed its origin. When this was destroyed, the heavy tropical rains soon washed away the soil, and has left a vast expanse of bare rock or sterile clay. This irreparable destruction was caused, in the first place, by goats, which were introduced by the Portuguese in 1513, and increased so rapidly that in 1588 they existed in the thousands. These animals are the greatest of all foes to trees, because they eat off the young seedlings, and thus prevent the natural restoration of the forest.’
Wallace is noticeably arguing in a language much closer to that of contemporary ecology and he goes on to be much more critical of human culpability.
‘They were, however, aided by the reckless waste of man. ‘The East India Company took possession of the island in 1651, and about the year 1700 it began to be seen that the forests were fast diminishing, and required some protection. Two of the native trees, redwood and ebony, were good for tanning, and, to save trouble, the bark was wastefully stripped from the trunks only, the remainder being left to rot; while in 1709 a large quantity of the rapidly disappearing ebony was used to burn lime for building fortifications!’*
In his work Tropical Nature and Other Essays (1878) Wallace is even more prescient.
‘In Central India the scanty and intermittent rainfall, with its fearful accompaniment of famine, is no doubt in great part due to the absence of a sufficient proportion of forest-covering to the earth’s surface; and it is to a systematic planting of all the hill tops, elevated ridges, and higher slopes that we can alone look for a radical cure of the evil. This would almost certainly induce an increased rainfall; but even more important and more certain, is the action of forests in checking evaporation from the soil and causing perennial springs to flow, which may be collected in vast storage tanks and will serve to fertilise a great extent of country; whereas tanks without regular rainfall or permanent springs to supply them are worthless…
… when the forests are cleared away the torrents of rain soon strip off the vegetable soil, and thus destroy in a few years the fertility which has been the growth of many centuries. The bare subsoil becoming heated by the sun, every particle of moisture which does not flow off is evaporated, and this again reacts on the climate, producing long-continued droughts only relieved by sudden and violent storms, which add to the destruction and render all attempts at cultivation unavailing. Wide tracts of fertile land in the south of Europe have been devastated in this manner, and have become absolutely uninhabitable. Knowingly to produce such disastrous results would be a far more serious offence than any destruction of property which human labour has produced and can replace; yet we ignorantly allow such extensive clearings for coffee cultivation in India and Ceylon, as to cause the destruction of much fertile soil which generations cannot replace, and which will surely, if not checked in time, lead to the deterioration of the climate and the permanent impoverishment of the country.
Wallace’s awareness of the risks of deforestation especially in tropical forests that were subject to heavy rainfall and how it would lead to soil erosion and desertification resonates with the drivers of biodiversity loss and environmental degradation today. His awareness, from his travels in the Amazon and in Indonesia, of the complex interrelationship between forest and cloud formation and his warning that extensive forest clearance, could also impact on climate is again a central narrative of the contemporary call to arms. His highlighting of the potential of ecological restoration to improve resilience in natural ecosystem services for human well-being is an argument at the centre of today’s debate. Wallace was writing this in the late 1800’s, a decade before the formation of the Sierra Club in the United States and the beginnings of the environmental and conservation movement.
It is clear then that more than a hundred years ago Wallace from framing the understanding on which much of current environmental policy now stands. While it is amazing to celebrate both Darwin’s and Wallace’s insights, Wallace in particular raises a particular question – why does there remain so much inaction and on-going call for more research evidence, when these primary human induced drivers of environmental change were so clearly highlighted more than a century ago?
* [Today the two redwood and ebony species survive on St Helena in a handful of specimens. The two species had been distinct, one living at lower elevations and the other higher. By the time the few remaining shrubby trees were transplanted to a safe conservation site on the ‘Scotland estate’ on the island they had also lost their natural pollinators. It is thought that introduced European bees allowed the few remaining plants to hybridise – the resulting ‘rebony’ has a little more hybrid vigor and may save the genes of the two species. The St Helena Conservation Trust is still trying to save these species along with the other threatened endemics on the island].
[You can find our much more about this environmental history in Wake of the Endeavour by Robert Bloomfield]