Anthropocene - an epoch that reflects human impact on Earth's history

The last ~10,000 years of the Earth's history, since the end of the "ice age" is called the Holocene epoch in the geological time scale. Likely proposed by Sir Charles Lyell in 1833, the Holocene was adopted by the International Geological Congress in 1885.

This it includes the period that covers all of human civillisation. Since then, mankind's activities have been so so impactful to the planet's climate and ecosystems as to be geological in nature.

In 2000, Paul Crutzen and Eugene Stoermer suggested that this influence of human behavior on the Earth constituted a new geological era, the "Anthropocene". ["The "Anthropocene"," by Paul J. Crutzen & Eugene F. Stoermer. Global Change Newsletter, 41: 17-18.]

Summarising previous observations of human impact in the literature and examples of the many global impacts, the authors then say,

"Considering these and many other major and still growing impacts of human activities on earth and atmosphere, and at all, including global, scales, it seems to us more than appropriate to emphasize the central role of mankind in geology and ecology by proposing to use the term "anthropocene" for the current geological epoch. The impacts of current human activities will continue over long periods."

They proposed the later part of the 18th century as the starting point, from when global effects become noticeable.

GSA Today just published a paper that makes an argument for its consideration as a formal epoch. The team of British geologists, all members of the Stratigraphy Commission of the Geological Society of London, ask, "Are we now living in the Anthropocene?"

"The term Anthropocene, proposed and increasingly employed to denote the current interval of anthropogenic global environmental change, may be discussed on stratigraphic grounds.

A case can be made for its consideration as a formal epoch in that, since the start of the Industrial Revolution, Earth has endured changes sufficient to leave a global stratigraphic signature distinct from that of the Holocene or of previous Pleistocene interglacial phases, encompassing novel biotic, sedimentary, and geochemical change.

These changes, although likely only in their initial phases, are sufficiently distinct and robustly established for suggestions of a Holocene-Anthropocene boundary in the recent historical past to be geologically reasonable.

The boundary may be defined either via Global Stratigraphic Section and Point ("golden spike") locations or by adopting a numerical date.

Formal adoption of this term in the near future will largely depend on its utility, particularly to earth scientists working on late Holocene successions. This datum, from the perspective of the far future, will most probably approximate a distinctive stratigraphic boundary."

- Zalasiewicza, J, M Williams, A Smith, TL Barry, AL Coe, PR Bown, P Brenchley, D Cantrill, A Gale, P Gibbard, FJ Gregory, MW Hounslow, AC Kerr, P Pearson, R Knox, J Powell, C Waters, J Marshall, M Oates, P Rawson & P Stone, 2008. Are we now living in the Anthropocene. GSA Today, 18 (2): 4-8.

Horseshoe crabs now date back to 445 MYA

"A remarkable new fossil horseshoe crab, Lunataspis aurora gen. et sp. nov., from recently discovered Upper Ordovician (c. 445 Ma) shallow marine Konservat-Lagerstätten deposits in Manitoba (Canada)."

See Rudkin, DM, GA Young & GS Nowlan, 2008. The oldest horseshoe crab: a new Xiphosurid from late Ordovician Konservat-Lagerstätten deposits in Manitoba, Canada. Palaeontology, 51(1): 1-9. and "Oldest Horseshoe Crab Fossil Discovered," by Jeanna Bryner. LiveScience.com, 28 Jan 2008.

This pushes back evidence for the mysterious horseshoe crabs by almost 100 million years, from 350 million to 445 million years ago. Having survived multiple extinction events during its geological existence, but habitat loss and marine pollution have seen significant localised loss of population numbers in some countries.

Present day horseshoe crabs appear to be similar to such fossils and we refer to them as "living fossils". In Singapore, Mandai mangroves appear to be a significant refuge for them. Let's hope we can extend their impressive record a little longer.

Human Genome Project

I am relooking at some notes and slides I prepared for this topic. Its an interesting topic not only because of the science behind it but also the ethical, social and legal implications (that makes the acronym "ELSI") which blur the lines between right and wrong. Here are two very good resources

The first is the NOVA programs. The videos capture authentic situations that individuals face with regards to genetic diseases and also feature the scientists, science behind the project. Its more information packed in multimedia than I can summarize in a set of lecture notes. More information meaning the drama of the video that will contribute to affective learning and hence motivate students to learn more about the subject.



The 2nd is this free,... yes free, online book you can download. Its easy to read and the examples giving illustrate clearly the perplexing "ELSI" issues about genetic testing, abortions, genetic determinism... that will surface once genetic tests become more accessible..



Think ELSI and genetic testing are still far off... well read this groundbreaking and probably as "Brave New World" as it can get article in the New York Times on how you can pay just under USD$1000 for the company 23andMe to scan your genome for 580,000 SNPs (Single Nucleotide Polymorphisms). You actually can order the kit.. not sure how it works but I guess you can do it at home for yourself and children. There are at least 3 companies who will do that for around that price.


Just spit..




This NYT journalist got her own genome scanned by just spitting saliva into a little test tube . Here's a snippet of the article titled "My Genome, Myself: Seeking Clues in DNA"

"I don't like brussels sprouts. Who knew it was genetic? But I have the snippet of DNA that gives me the ability to taste a compound that makes many vegetables taste bitter. I differ from people who are blind to bitter taste -- who actually like brussels sprouts -- by a single spelling change in our four-letter genetic alphabet: somewhere on human chromosome 7, I have a G where they have a C."

But that's just information.... trivia about your genes. It gets more serious when people actually use that information to determine the genetics of their progeny. This couple actually had their daughter "genetically determined" so that she wouldn't inherit forms of genes that would make her highly susceptible to a certain form of colon cancer. This testing is termed preimplantation genetic diagnosis, or P.G.D., which means you need to cull embryos to get the right one. An eight-cell embryo has gone through fertilization.

For this couple, 4 were culled leaving 10 good ones that didn't have those forms of genes that cause cancer, 2 more were culled when a Down's syndrome test was done. Think that is unethical? Well there are people who actually remove their large intestines or breasts as a prophylactic measure against such cancers once they find they harbour just the forms of genes that make them susceptible. They may have siblings who have died because of that disease. Watch the 3rd video called One Wrong Letter in the set of videos on Nova and you will know why it becomes so grey.

(thanks to Kevin Lam who pointed out the genome scan link).

"New Marvels" from Costa Rica

New species discovered in Costa Rica, including a dwarf salamander no longer than a thumbnail. Research was conducted by scientists from the Natural History Museum, London funded by the Darwin Initiative. Press release from the NHM.

Giant fungus

The Devonian fossil Prototaxites, long a puzzle thought to be a vascular tree species, may actually be a fungus.... C. Kevin Boyce of the University of Chicago and co-workers used isotopic ratios to show that it was more likely to be a heterotroph than an autotroph, and based on its anatomy it was most likely to have been a fungus.

Journal reference: Geology, May 2007; v. 35; no. 5; p. 399–402; doi: 10.1130/G23384A.1