Unsolved puzzle

With reference to Nicobar people aren’t Africans (May 9) the author has rounded off the story with a note of ambiguity. How come the Mundaris and the Nicobarese have independent origins despite belonging to the same linguisic family? Their languages must be sharing certain distinctly common characteristics, or else, the issue of of establishing a common ancestry would not have cropped up. Such unsolved puzzles provides useful clues to human ancestry.

Arjun Chaudhuri
Bhowanipore

Chemical fighter

This refers to Extra cheer (May 9) in which the author has talked about thousands of biochemical reactions which take place in our body to sustain life. The reactions generate lots of oxygen-rich free radicals (reactive oxygen species, or ROS). Those radicals adversely affect DNA, RNA and other molecules of our body cells. The effects of ROS on body chemistry are thought to be the most important cause of ageing of the animal body. The deleterious effects are also responsible for cancer, heart diseases, cerebral attacks, senile dementia, Alzheimer's disease etc. To counter these damaging chemicals nature has provided us with many in-built antioxidant devices (such as glutathions); they constantly try to minimise the amount of ROS in our body. Also, we eat a lot of plant chemicals to combat these chemicals. Green tea has in it a chemical called epigallocatechin, which is a super-efficient anti-oxidant.

Arun Laha
Howrah

Psychiatric dilemma

With reference to Extreme mania (May 9) I wonder why people who suffer from the enigmatic ailment called Body Integrity Disorder don’t get themselves treated psychiatrically, instead of getting their body parts amputated.

Arunendu Sarkar
Nadia