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Plant life
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THE LAST WORD Cracked it
n Cracked heels can start with calluses brought on by friction caused by ill-fitting shoes. If this skin dries or has a fungal infection, it loses its elasticity and is prone to cracking. This can be exacerbated by ageing, weight, psoriasis and diabetes. Urea can penetrate the skin’s
outermost layer. Here it readily suggest that the eukaryotic cell absorbs and retains water, evolved from the archaea. promoting rehydration of the The eukaryotic cell gained its skin. At concentrations of 40 per supremacy from its engulfment cent, urea causes the layer to of, and symbiosis with, loosen and exfoliate, diminishing a bacterium that became the the likelihood of cracking. Also, mitochondrion. This oxidises by improving the hydration of food molecules to provide the skin, urea makes it more “Early life gave us two permeable to topical drugs, different groups of enhancing treatment of prokaryotic cells, infections and inflammation. archaea and bacteria” David Muir Edinburgh, UK energy for all the other chemical processes of the cell. Separating these chemical pathways from the Plant life rest of the cell gave the eukaryote A recent New Scientist article, a huge metabolic advantage. So, “The most ancient piece of you” we are all descended from both (4 November 2017), discussed the archaea and eubacteria (which common ancestors of living beings have a rigid cell wall), and our today. But are plants included in this mitochondria have their own universal common ancestor? If so, DNA and bacteria-like ribosomes. are we linked to plants in very early The next key symbiosis was stages of evolution? when a mitochondria-containing eukaryote cell engulfed a n The short answer is yes, very photosynthetic bacterium, which much so. Leaving aside what may became the chloroplast (a process have happened in the primordial that happened more than once). ooze, early life consisted of simple These cells could now use light prokaryotic cells. These used DNA to create their food, making them as their genetic mechanism, but it the first plants. The different was not segregated from the rest requirements for finding food as of the cell as it is in the more opposed to capturing light soon advanced eukaryotic cells that led to the differences between make up plants, animals and fungi. plants and animals we see today. There were two different groups But we are all related. of prokaryotic cells – archaea and Guy Cox bacteria – with a huge variety of Australian Centre for Microscopy metabolic systems. Both bacteria and Microanalysis, and archaea are still widespread University of Sydney, Australia today. How the eukaryotic nucleus evolved is still unclear, n Inference from genetic data but key biochemical pathways suggests humans and plants last
We pay £25 for every answer published in New Scientist. To answer a question or ask a new one please email [email protected]. Questions should be scientific enquiries about everyday phenomena, and both questions and answers should be concise. We reserve the right to edit items for clarity and style. Please include a postal address, daytime telephone number and email address. You can also send questions and
answers to The Last Word, New Scientist, 25 Bedford Street, London, WC2E 9ES. New Scientist Ltd retains total editorial control over the published content and reserves all rights to reuse question and answer material that has been submitted by readers in any medium or in any format and at any time in the future. All unanswered questions and previous questions and answers are at newscientist.com/lastword/
Why do I, or any other human, get sore and cracked heels? I understand it’s less common in men than women – presumably this is down to footwear choices? The cream product I use to cure it works very well, but its active ingredient appears to be urea. How does this react with my skin to cure the problem?
n The commonest reasons for sore and cracked heels are a failure to remove a build up of keratin around the heels or an infection. Pressure from footwear and excessive weight can cause a dense layer that stresses the underlying tissue. Extra physical effort, other than normal showering, is needed to remove it. Rubbing any emollient into the skin helps, but those containing urea help specifically by drawing water into the keratin. Opportunistic fungal skin infections, such as tinea pedis, can contribute to the severity of the problem, and should be suspected if the cracks do not respond to heel creams. Celia Drakard Registered podiatrist Woodbridge, Suffolk, UK
shared a common ancestor around 1.6 billion years ago. This is substantially later than the last common ancestor of all life (assuming life evolved just once), which may have existed up to 3.8 billion years ago. This is because plants, animals, fungi and protists (such as slime moulds) all form a major grouping derived from eukaryotic cells, which evolved relatively recently in life’s history. For several billion years after life’s origin, it would have existed in a form more similar to the relatively simple prokaryotic cells that characterise bacteria and archaea today. Eukaryotic cells have membrane-bound compartments inside them, such as the enclosed nucleus containing the cell’s DNA. Believe it or not, animals and fungi are more closely related to each other than either of them is to plants, based on genetic dating of the lineage divergences within the eukaryotes. Sam Buckton Churchill College, Cambridge, UK n For an account of the search for the last universal common ancestor, or LUCA, may I recommend Richard Dawkins’s book The Ancestor’s Tale. It takes the form of a Chauceresque pilgrimage back through our evolutionary tree, meeting common ancestors each time a fork joins our path. Edna Richards Welwyn Garden City, Hertfordshire, UK
THE LAST WORD Cracked it
n Cracked heels can start with calluses brought on by friction caused by ill-fitting shoes. If this skin dries or has a fungal infection, it loses its elasticity and is prone to cracking. This can be exacerbated by ageing, weight, psoriasis and diabetes. Urea can penetrate the skin’s
outermost layer. Here it readily suggest that the eukaryotic cell absorbs and retains water, evolved from the archaea. promoting rehydration of the The eukaryotic cell gained its skin. At concentrations of 40 per supremacy from its engulfment cent, urea causes the layer to of, and symbiosis with, loosen and exfoliate, diminishing a bacterium that became the the likelihood of cracking. Also, mitochondrion. This oxidises by improving the hydration of food molecules to provide the skin, urea makes it more “Early life gave us two permeable to topical drugs, different groups of enhancing treatment of prokaryotic cells, infections and inflammation. archaea and bacteria” David Muir Edinburgh, UK energy for all the other chemical processes of the cell. Separating these chemical pathways from the Plant life rest of the cell gave the eukaryote A recent New Scientist article, a huge metabolic advantage. So, “The most ancient piece of you” we are all descended from both (4 November 2017), discussed the archaea and eubacteria (which common ancestors of living beings have a rigid cell wall), and our today. But are plants included in this mitochondria have their own universal common ancestor? If so, DNA and bacteria-like ribosomes. are we linked to plants in very early The next key symbiosis was stages of evolution? when a mitochondria-containing eukaryote cell engulfed a n The short answer is yes, very photosynthetic bacterium, which much so. Leaving aside what may became the chloroplast (a process have happened in the primordial that happened more than once). ooze, early life consisted of simple These cells could now use light prokaryotic cells. These used DNA to create their food, making them as their genetic mechanism, but it the first plants. The different was not segregated from the rest requirements for finding food as of the cell as it is in the more opposed to capturing light soon advanced eukaryotic cells that led to the differences between make up plants, animals and fungi. plants and animals we see today. There were two different groups But we are all related. of prokaryotic cells – archaea and Guy Cox bacteria – with a huge variety of Australian Centre for Microscopy metabolic systems. Both bacteria and Microanalysis, and archaea are still widespread University of Sydney, Australia today. How the eukaryotic nucleus evolved is still unclear, n Inference from genetic data but key biochemical pathways suggests humans and plants last
We pay £25 for every answer published in New Scientist. To answer a question or ask a new one please email [email protected]. Questions should be scientific enquiries about everyday phenomena, and both questions and answers should be concise. We reserve the right to edit items for clarity and style. Please include a postal address, daytime telephone number and email address. You can also send questions and
answers to The Last Word, New Scientist, 25 Bedford Street, London, WC2E 9ES. New Scientist Ltd retains total editorial control over the published content and reserves all rights to reuse question and answer material that has been submitted by readers in any medium or in any format and at any time in the future. All unanswered questions and previous questions and answers are at newscientist.com/lastword/
Why do I, or any other human, get sore and cracked heels? I understand it’s less common in men than women – presumably this is down to footwear choices? The cream product I use to cure it works very well, but its active ingredient appears to be urea. How does this react with my skin to cure the problem?
n The commonest reasons for sore and cracked heels are a failure to remove a build up of keratin around the heels or an infection. Pressure from footwear and excessive weight can cause a dense layer that stresses the underlying tissue. Extra physical effort, other than normal showering, is needed to remove it. Rubbing any emollient into the skin helps, but those containing urea help specifically by drawing water into the keratin. Opportunistic fungal skin infections, such as tinea pedis, can contribute to the severity of the problem, and should be suspected if the cracks do not respond to heel creams. Celia Drakard Registered podiatrist Woodbridge, Suffolk, UK
shared a common ancestor around 1.6 billion years ago. This is substantially later than the last common ancestor of all life (assuming life evolved just once), which may have existed up to 3.8 billion years ago. This is because plants, animals, fungi and protists (such as slime moulds) all form a major grouping derived from eukaryotic cells, which evolved relatively recently in life’s history. For several billion years after life’s origin, it would have existed in a form more similar to the relatively simple prokaryotic cells that characterise bacteria and archaea today. Eukaryotic cells have membrane-bound compartments inside them, such as the enclosed nucleus containing the cell’s DNA. Believe it or not, animals and fungi are more closely related to each other than either of them is to plants, based on genetic dating of the lineage divergences within the eukaryotes. Sam Buckton Churchill College, Cambridge, UK n For an account of the search for the last universal common ancestor, or LUCA, may I recommend Richard Dawkins’s book The Ancestor’s Tale. It takes the form of a Chauceresque pilgrimage back through our evolutionary tree, meeting common ancestors each time a fork joins our path. Edna Richards Welwyn Garden City, Hertfordshire, UK