In the past few decades, thousands of extra-solar planets have been discovered within our galaxy. As of July 28th, 2018, a total of 3,374 extra-solar planets have been confirmed in 2,814 planetary systems. While the majority of these planets have been gas giants, an increasing number have been terrestrial (i.e. rocky) in nature and were found to be orbiting within their stars' respective habitable zones (HZ).
However, as the case of the Solar System shows, HZs do not necessary mean a planet can support life. Even though Mars and Venus are at the inner and the outer edge of the Sun's HZ (respectively), neither is capable of supporting life on its surface. And with more potentially-habitable planets being discovered all the time, a new study suggests that it might be time to refine our definition of habitable zones.
Welcome to the Inhospitable Zone.
(Score: 1, Informative) by Anonymous Coward on Wednesday August 01 2018, @11:10AM (1 child)
Living cells always communicate using chemical signals, even in multicellular organisms and even in animal bodies. Neural cells are just an adaptation useful to shorten reaction times by electrically commanding release of chemical signals at remote cell boundaries.
Now, when you have a community of cells without specialized, channelized information pathways, then the selectivity of information reception must be achieved by some sort of chemical addressing and receptors specialized for each of the signals (and we still have those, it is "endocrine system", hormones and receptors). Supposedly, the "intelligence", or complexity of interactions and cooperation between undifferentiated uni-cells contained in group entities should be proportional to number of kinds of different receptors they have, but their decision making ability should be limited by the size of their group, unless some sort of hierarchy (tiers, like in neural networks) or specialization is introduced.
(Score: 2) by fyngyrz on Wednesday August 01 2018, @03:09PM
FTFY.
Also, our not-necessarily-complete experience in this is limited to this planet, something that in no way provides an ironclad framework for what might be going on on other planets and in other star systems. Ergo, "habitable zone" may well be complete nonsense.