More than 65,000 years ago, a Neanderthal painted in red ochre on the wall of a cave.
Modern humans moved into Spain about 40,000 years ago, replacing Neanderthals who were there 120,000 years ago. In Science magazine last week, scientists at Southampton, Durham and Leipzig describe and date calcite crystals that had grown on top of the pictures.
In a second paper, published in Science Advances, D. Hoffman et al describe dyed and decorated seashells found in a cave in southeast Spain. They were made by Neanderthals 115,000 years ago.
A show that runs until February is at Mexico City’s Palace of Fine Arts. “Mexican Red, the Cochineal in Art,” traces use of this pigment from the highlands of pre-Hispanic Mesoamerica to Europe.
There, it became increasingly associated with the projection of power in the 17th and 18th centuries. Cochineal fell into decline in the 19th century, as synthetic dyes were introduced, but was sought out later by the Impressionists.
The cochineal is a Mexican insect that is the source of the dye. This specimen is on display at the exhibition. (Credit Marco Ugarte/Associated Press)
The cochineal insect feeds on the prickly pear cactus and was cultivated domestically in Mexico and Peru in pre-Hispanic times. The female can be dried and crushed to extract the red carminic acid. Additives of different acidity produce shades that range from light pink to a deep purple. (New York Times, November 28th)
Next year will be the 400th anniversary of the death of Sir Walter Raleigh (1654 – 29 October 1618). He was an English chemist, poet, soldier, politician, courtier, spy and explorer.
As well as popularising the use of tobacco in England Raleigh was interested in chemistry.
statue in N Carolina
Raleigh was betrayed by Sir Lewis Stukley with evidence that he cheated the Spanish in war. For this, Raleigh was eventually executed. During a long imprisonment in the Tower of London he was allowed to study inorganic chemistry. This interest was stimulated by his experience as a miner in Cornwall and Devon where he owned large estates. Raleigh was also a popular poet. His friend, Thomas Tyndale, had a draft of verse composed to mark Raleigh’s grave in the Palace of Westminster:
On Sir Walter Raleigh /Here lieth, hidden in this pitt, / The wonder of the world for witt. / To small purpose did it serve; / His witt could not his life preserve. / His living was belov’d of none, / Yet in his death all did him moane. / Heaven hath his soul, the world his fame, /The grave his corpse, Stukley his shame.
In 1662 Catherine of Braganza (daughter of Portugal’s King John IV) married King Charles II. Her dowry included money, spices, treasures and the lucrative ports of Tangiers and Bombay. From there, she began to drink the loose-leaf tea, known then as Transporte de Ervas Aromaticas, or T.E.A.
(Credit: DEA/G. DAGLI ORTI/Getty Images)
When Catherine arrived in England, tea was being consumed there only as a medicine to invigorate the body and keep the spleen free of obstructions. But the young queen extended that habit and made it popular as a social beverage as well as a health tonic. The poet Edmund Waller wrote to her shortly after her arrival in London with a poem that linked the queen and Portugal with the fashionable status of tea in England.
“The best of Queens, and best of herbs, we owe To that bold nation, which the way did show To the fair region where the sun doth rise, Whose rich productions we so justly prize.”
Tea was very expensive because it came from China and it was taxed very heavily,
and only the most rich members of society could afford it. So tea became associated with elite women’s sociability around the royal court.
When the leaves of tea plants are dried, flavonoid-type polyphenols remain. It is these that produce the characteristic colour and taste.
The tea polyphenols have been reported in various research to exhibit antioxidant properties. Antioxidants have been touted as having a range of health benefits, but the scientific evidence for these is still a little vague in parts. Studies have shown that antioxidants can protect cells from damage as a result of free radicals – molecules with an unpaired electron – but the results of some longer term trials have been inconclusive as to their efficacy, particularly in cancer treatments.
In July 2017’s journal ACS Chemical Biology, M Golczak and J Silvaroli show what happens when you cut an onion.
A so-called Lachrymatory Factor (LF) is formed by the release of two chemicals that are released by the cutting of cell walls. One is a sulfenic acid precursor. The other is an enzyme called alliinase which is normally contained within the cells’ vacuoles. Upon release the two react to form something like tear gas.
garlic, an alliinase enzyme acts on the chemical alliin converting it into allicin. The process involves two stages: elimination of 2-propenesulfenic acid from the amino acid unit (with α-aminoacrylic acid as a byproduct), and then condensation of two of the sulfenic acid molecules.
There are a range of similar enzymes that can react with the cysteine-derived sulfoxides present in different species. In onions, an isomer of alliin, isoalliin, is converted to 1-propenesulfenic acid. A separate enzyme, the lachrymatory factor synthase or LFS, then converts this chemical to a potent LF.
Pulse, the Linnean Society’s newsletter 34, June 2017, has an article entitled Lampblack and Lead, by E. Rollinson.
(H. Bradbury, 1843, 1859)
It tells how G. Cardano gave instructions back in 1550: ‘A fresh leaf is rubbed with verdigris and carbon; soaked in the right amount of colour it is printed on one of two large sheets of paper, so that an almost life-like image remains.’ (De Subtitilitate, Book XIII). Earlier, a physician named Conrad von Butzbach, in his 1425 Codex Auratus, coated paper with oil and used soot from a candle flame to make an impression of a plant specimen.