Happy Christmas to all my readers!

The Christmas fresco above, by Giotto, shows the Star of Bethlehem as a comet (top centre). It is likely that this fresco depicts Halley’s Comet, which Giotto saw in 1301, about two years before he began the series of frescos of which this is part. This work by Giotto was celebrated in the name of the Giotto spacecraft, which observed the comet in 1986.

Let me take this opportunity to wish all my readers a very happy Christmas (and apologies for duplicating a previous post).

A sample of elements

  • Helium (He, element 2) – used in balloons, because it is lighter than air
  • Carbon (C, element 6) – one of the key elements in living things
  • Nitrogen (N, element 7) – makes up 78% of the atmosphere
  • Oxygen (O, element 8) – makes up 21% of the atmosphere
  • Aluminium (Al, element 13) – a light metal used to make saucepans and aeroplanes
  • Silicon (Si, element 14) – used to make electronics
  • Phosphorus (P, element 15) – used in elemental form on the side of matchboxes
  • Sulfur (S, element 16) – a widely used element which occurs naturally in elemental form
  • Titanium (Ti, element 22) – a light, strong metal
  • Iron (Fe, element 26) – the most widely used metal (mixed with other elements it becomes steel)
  • Copper (Cu, element 29) – a metal that has been used for about 10,000 years, named after the island of Cyprus
  • Zinc (Zn, element 30) – used in batteries and to prevent corrosion
  • Silver (Ag, element 47) – widely used in jewellery since ancient times (the symbol is from the Latin argentum)
  • Tin (Sn, element 50) – about 5,000 years ago, tin (Latin stannum) was mixed with copper to produce bronze
  • Iodine (I, element 53) – dissolved in alcohol, it is used as a disinfectant
  • Gold (Au, element 79) – widely used in jewellery since ancient times (the symbol is from the Latin aurum)

For more on the elements, see the fantastic book The Elements by Theodore Gray of periodictable.com, which I have previously reviewed.

Ecological literacy and Frank Herbert’s Dune, half a century on

Dune by Frank Herbert

The year 1965 saw the appearance of what has been called “the first planetary ecology novel on a grand scale.” Frank Herbert’s Dune explored a plethora of interesting themes, notably that of ecology. The novel speaks of “… teaching [the children] ecological literacy, creating a new language with symbols that arm the mind to manipulate an entire landscape, its climate, seasonal limits, and finally to break through all ideas of force into the dazzling awareness of order.

The use of food webs, like the one for waterbirds of Chesapeake Bay above, was fairly standard by 1965, and Herbert seems to be hinting at a graphical language for ecology going beyond that. Exactly what he was referring to is unclear.

But are we teaching the kind of ecological literacy Herbert refers to? A 2013 survey indicated that, out of 145 US tertiary institutions ranked for “Ecology and Evolutionary Biology” and “Integrative Biology,” only 47% taught a course in ecosystem ecology or biogeochemistry, and only 22% of the courses included field experiences. A 1993 survey of UK secondary teaching (A-levels and GCSE) showed that students only studied a median of 2 or 3 different habitats:

So how many children actually understand, say, trophic cascades in the wolf–elk ecosystem? How many adults, for that matter? The evidence suggests that it’s not very many, judging by the resistance to sensible management of National Parks. If we do not wish to recreate the desert planet Arrakis, we might like to work on that.


Homeopathy is an alternative medicine based, in large part, on extremely dilute solutions of illness-producing agents. For example, diluted coffee is used to treat insomnia.

Given the levels of dilution used, and the fact that 18 grams of water (about one tablespoon) contains about 6 × 1023 molecules, this means that homeopathic medicines generally contain zero molecules of the active ingredient – that is, they are generally plain water. The 10:23 anti-homeopathy campaign is based on that idea:

Last year, the Australian National Health and Medical Research Council (NHMRC) completed a review of the effectiveness of homeopathy, concluding that there are no health conditions for which there is reliable evidence that homeopathy is effective because no good-quality, well-designed studies with enough participants for a meaningful result reported either that homeopathy caused greater health improvements than placebo, or caused health improvements equal to those of another treatment.

See also a blog post by the report chair here, or listen to this interview with Edzard Ernst, former Professor of Complementary Medicine at Exeter. XKCD makes an economic argument about effectiveness:

Failure to collect type specimens of new species considered harmful

A September 2016 letter to Nature defended the naming of new species without the traditional type specimen. Some months earlier, Nature had an editorial on the same subject.

A group of 493 concerned taxonomists responded by saying that type specimens were essential for objectivity and replicability. Nature would not publish their letter, and so it appeared in Zootaxa in November. And they are right, of course – even with the ability to go back and check preserved specimens (especially their DNA), taxonomy can be a tricky business. Without that ability, it would be a nightmare.