Thursday, 26 March 2015

The beginning and the end of the Anthropocene

Is there an Anthropocene? This question is being debated currently and a report is to be published in 2016 on whether a geological epoch created by the transformative activities of Homo sapiens should be defined, and what should mark its beginning. According to Richard Monastersky [1]:

A committee of researchers is currently hashing out whether to codify the Anthropocene as a formal geological unit, and when to define its starting point.. .. The push to formalize the Anthropocene upsets some stratigraphers.. ..One major question is whether there really are significant records of the Anthropocene in global stratigraphy.. ..Some researchers argue that it is too soon to make a decision – it will take centuries or longer to know what lasting impact humans are having on the planet.

Monastersky then quotes from Erle Ellis, a Geographer at the University of Maryland:

"We should set a time, perhaps 1000 years from now, in which we would officially investigate this.. ..Making a decision before then would be premature."

Discussion about the Anthropocene thus reflects a typical debate among scientists and other academics having different views of what marks a definable stratigraphic boundary.

As Monastersky points out, markers could be from the Industrial Revolution, or from the radioisotope signatures resulting from atmospheric testing of nuclear weapons that ceased in the 1960s. While supporting the case for 1964 as the beginning of the Anthropocene, Lewis and Maslin [2] also put forward a strong argument for using the measurable decrease in atmospheric carbon dioxide between 1570 and 1620 (with a minimum in 1610), something that they relate to the effects of New World colonisation and dramatic changes in human population density, changes in diet and agricultural practices brought by new foods, and the development of increased trade based on industrial production. Their selection of 1610 adds another part to the Anthropocene debate, but their paper also contains an interesting review of human impacts in the very short time that Homo sapiens has been the dominant species on the Earth.

In conclusion, Lewis and Maslin write [2]:

Past scientific discoveries have tended to shift perceptions away from a view of humanity as occupying the centre of the Universe. In 1543 Copernicus's observation of the Earth revolving around the Sun demonstrated that this is not the case. The implications of Darwin's 1859 discoveries then established that Homo sapiens is simply part of the tree of life with no special origin. Adopting the Anthropocene may reverse this trend by asserting that humans are not passive observers of Earth's functioning. To a large extent the future of the only place where life is known to exist is being determined by the actions of humans. Yet, the power that humans wield is unlike any other force of nature, because it is reflexive and therefore can be used, withdrawn or modified. More widespread recognition that human actions are driving far-reaching changes to the life-supporting infrastructure of Earth may well have increasing philosophical, social, economic and political implications over the coming decades.

Whether the Anthropocene should be defined, and what its definition should be, seem trifling issues compared with those raised in that last paragraph. Whether the Anthropocene began in 1610 or 1964, it has the potential to be one of the shortest epochs thus far. The end of a geological time period is usually marked by large-scale events such as asteroid impacts, widespread upheavals in the Earth’s crust, or dramatic changes in climate. We don’t know how the Anthropocene will end and it may be from one of these causes and thus be outside human control. Alternatively, the epoch may end as a direct result of human actions. We know how destructive we have already been, and continue to be; with wars, global warming, widespread removal of forests, extinction of populations, introduction of poisons and antibiotics, etc. all being major impacts. There are those who feel that we should be able to overcome the many difficulties we face using technological solutions but, while I admire human invention, I do not feel optimistic about the future. The dominant economic system is based on growth and growth cannot be sustained indefinitely, so those of us in the Developed World will no longer be able to cocoon ourselves in warmed (or cooled) buildings and we may need to hunt and forage to obtain food. The social crises that result from a catastrophic fall in living standards can be imagined.

This is preachy, but our way of life, and its characteristic complacency, is highly damaging for other organisms on Earth and, like all the others, our epoch will end. The Anthropocene will be followed by another epoch, but what organisms will dominate? After our controlling influence is no longer present, the environment will again be the main vehicle for selection of changes in genes (a natural mechanism that we override). Bacteria and other unicellular organisms are sure to survive the cataclysmic events at the end of the Anthropocene, but what about other organisms? Will evolution result inevitably in a dominant form that makes drastic changes to its surroundings, or will there be a less destructive solution to the relationship between organisms and their environment?

[1] Richard Monastersky (2015) The human age. Nature 519: 144-147.

[2] Simon L. Lewis and Mark A. Maslin (2015) Defining the Anthropocene. Nature 519: 171-180.

Wednesday, 4 March 2015

Eating limpets

In my last blog post, I wrote an appreciation of limpets and the extraordinary adaptations that they show for life on rocky marine shores [1]. As I pointed out, that should not prevent us from using these molluscs as a source of food and that is something that fits with contemporary debates about sustainability and the need for animal protein. We are now much less resourceful than our ancestors, and are dependent on what is available in stores or on market stalls, with the latter often showing a more local approach than the former.

To gain an historical perspective on eating limpets, I read Lovell's The Edible Molluscs of Great Britain and Ireland with Recipes for cooking them [2] and he describes their consumption by some communities:

"In many places limpets are used for food, especially on the Continent, where they are oftener eaten than the periwinkle. At Naples they make them into soup, and I am told it is an excellent dish.. ..The poorer classes at Eastbourne eat them constantly.. ..At Plymouth they gather great numbers of them, especially from the breakwater, as well as in the Isle of Man, where they are known by the name of "flitters"; and in Scotland the juice of these shellfishes is mixed with oatmeal.."

In addition to this background information, Lovell also gives recipes [2]:

"Limpet Soup – Wash them, and free the shells from seaweeds etc.; put them into a saucepan and parboil them. Take them out of the shells; chop up some parsley, and put it, with a tablespoonful of oil, or an ounce of lard or butter, into a saucepan, and fry until it becomes brown. Add a pint of water, and, when boiling, throw in the limpets, with a teaspoonful of anchovy sauce, some pepper, and boil again for half an hour; or, if preferred, stew them before putting them into the soup.

Limpet sauce – Choose clean-shelled limpets, not covered with barnacles, steep them in fresh water, and then heat them in a close covered saucepan until they part easily from the shells. They yield a rich brown liquor, in which, after being shelled, they may be stewed for half an hour. Thicken the liquor with butter and flour; strain and season with pepper, cayenne, and salt, and a slight flavouring of lemon-juice or vinegar. The limpets, being tough and indigestible, are not returned into the sauce."

The latter comment reminds us of the common failing of over-cooking seafood of all kinds, something that one learns by trial and error.

Lovell [2] also gives a more rustic approach to cooking limpets, originating from the island of Herm in the Channel Islands, and reported by Jeffreys in Volume 3 of his British Conchology:

"Roasted limpets - The limpets were placed on the ground, and laid in their usual position, and cooked by being covered with a heap of straw, which had been set on fire, about twenty minutes before dinner."

To these recipes can be added others from different parts of the World (illustrations of each dish are given, with the URL to the web page for each recipe):

It is only possible to eat limpets as a regular part of the diet if one lives at, or near, the coast. For those who are landlocked, Lovell guides us to Garden Snails, together with their close relatives, including the Roman, or Vine, Snail (and who doesn't like Escargots à la Bourguinonne?). Limpets and land snails are both sustainable foods and provide good sources of animal protein. Although I don't feel comfortable about roasting them alive, placing the molluscs in boiling water kills them rapidly and they can also be kept in a deep freeze for a short time to reduce their metabolism severely before they are cooked.

Mark Zuckerberg became famous not only for Facebook, but also for his statement that killing animals oneself is better than willingly being ignorant of how we obtain the meat we buy from butchers or supermarkets [3]. For those that would like to follow Mr Zuckerberg's example, but cannot face the prospect of cutting the throat of a pig or a goat, killing snails of various kinds provides rather less of a challenge.   

[2] M. S. Lovell (1867) The Edible Molluscs of Great Britain and Ireland with Recipes for cooking them. London, Reeve & Co.