Gather The Tangled Tree: A Radical New History Of Life Developed By David Quammen Accessible In File

Book Award Longlist for Nonfiction, Wowwhere to start Probably the most blow your mind thing is thatof the human genome originated in virus genomes, This is just one of the insights resulting from scientists studying molecular phylogenetics, where the study of DNA and RNA in different species allows them to discover the evolutionary relationship among them.
One such retrovirus genome fragment is found in placentas and helps to transfer nutrients between the mother and child, Sothis is a retrovirus genome fragment that humans have benefitted from, However, other retroviruses arent so benevolentthey are found in some leukemias and HIV,

How did viruses get into the human genome Through a process call horizontal gene transfer HGT, This is a process whereby genes pass on genetic material directly and is absorbed into the new DNA and can then be passed on vertically from parents to offspring, Not surprisingly, HGT is more prevalent in simpler life forms, like bacteria, Soremember the many bacteria species found in the human GI tract Now, what happens when an antibioticresistant bacteria finds its way in your small intestine There might be some cute little viruses there too.
And they help to transfer that resistance to many of the other bacteria, The result is the avalanche of bacteria species that become resistant to that antibiotic,

There are some biological forms that are particularly susceptible to HGT things like rotifers, These guys look like microscopic sucking organisms and feed on bacteria, algal cells, small protozoans and organic detritus and are probably prevalent in our rain gutters, They absorb all sorts of genome bits and they have been shown to transfer those to fruit flies,

In addition, Quammen covers the discovery inby biologist Carl Woese of a third domain of living organisms, which he called Archaea, These microorganisms were once considered a form of bacteria, but its cell walls are completely different, allowing it to live in extreme environments like hot springs and salty ponds, Further, its DNA is in some ways closer to the domain Eukarya organisms like us with cells with a nucleus, than regular bacteria Eubacteria,

Be reassured, DarwinsOrigin of the Species is not dispelled, It just got more complicated, Highly recommend.
A large part of the book was about Carl Woese, a character who was odd, but about whom I really could not care, He used early, difficult sequencing techniques to identify the Archaea, an entirely separate form of life, different from bacteria, plants, and animals, But since this was already old news when I had Bioin, I already knew about the Archaea, and the details of its discovery and identification just weren't that riveting the way they're presented here.


More interesting although, again, already known to me, and not that interesting in the details of its discovery, was the realization inthat it was DNA that could transform a benign bacterium into a virulent one, through "infective heredity.
". The interesting part of that was how early this was known, how early we knew how difficult it would be to keep ahead of bacteria in the resistance area,

But then things get interesting, I didn't know the overall phrase "horizontal gene transfer, " Transformation, in the above sense, was one transfer of genetic material from a dead bacterium to a live one, A second was conjugation, a sort of "sex" between bacteria, The other involves viruses carrying foreign DNA into the cells they infect, called transduction,

Evidence of bacteria that were resistant to various antibiotics before the human populations in which they were found were exposed to those abx because they are derived from plant compounds in the first place

Maurice Panisset, in A New Bacteriology, made "the case that all bacteria on Earth constitute a single interconnected entity, a single species no, wait, maybe even a single individual creature through which genes from all the variously named 'species' flow relatively freely, by horizontal gene transfer, fo ruse where needed"a "superorganism" idea related in spirit, but not particulars, to Margulis's Gaia hypothesis and the idea that mitochondria had once been freeliving bacteria"

And when they started looking, scientists found horizontal transfer everywhere bacterial genes in fish and plants.
Sea urchins one to another, though their lineages had been separate formillion years, E. coli to a fungus, brewer's yeast, some microbes are eukaryotic so they come in three flavors, since there are also bacteria and archaea, Bdelloids which have only females, having gone without sex forM years, scientists have "found all sorts of craziness that shouldn't have been there, More specifically, they found at least twentytwo genes" from bacteria, fungi, and plants, A few were still functional,of bdelloid genes had been acquired from bacteria "or other dissimilar creatures",

One parasitic bacteria infects the germline eggs of insects, and has managed to get itself included in the host's genome one fruit fly has incorporated the entire Wolbachia genome into its own DNA.
The same researcher found that bacterial DNA can be found in normal human genomes, but they are "times more common in tumor cells than in healthy cells", "In leukemia cell genomes, they found stretches resembling the DNA of Acinetobacter bacteria, a group that includes infectious forms often picked up in hospitals, In the stomach tumor genomes, they found pieces suggesting Pseudomonas, . . " The genome of one cabbagerelated plant isbacterial, A fungus containsgenes from bacteria and archaea, The human genome contains,letters of bacterial DNA transferred from our mitochondria endosymbiotic gene transfer,

And there's more: in one study, researchers looked at the genomes of,complete bacterial genomes, half o fthem closely associated with humans, along with their ecological where on/in the body and geographic where in the world provenance.
They looked for close matches in the genes, which would "signal a relatively recent horizontal transfer event for that gene", They found,incidents. What predicted transfer "The shared ecology of the human gut, or the vagina, or the nasal passages, or the skin, was most conducive to horizontal transfer, The shared phylogeny of membership in the same bacterial lineage came second, The shared geography of the same continent was a weak third, "

Dunning HOtopp's research faced "adamant resistance among a few influential biologists, including some Nobel Prize winners, to her and her colleagues' discoveries of HGT in the animal kingdom.
'No, it's got to be an artifact, You have to be able to explain it some other way, ' Animals don't experience horizontal gene transfer, period, Humans, certainly not.

"'Do you ever say to them, "Is that a faithbased statement" I asked, What I meant was: it seemed almost as though the Weismann barrier had become a theological dogma,

"She mused about that for a moment and allowed that some scientists did appear to be more

religious about science than about religion, A touch of faithbased genomics 'I think it is,' she said, ".

Jim Brown and Ford Doolittle looked atdifferent proteins "that are essential to all forms of life, and at the different variatns of those proteins as reflected in more than,different gene sequences, from a wide variety o fbacateria, archaea, and eukaryotes.
They constructed an indvidiual tree for each of the sixty six proteins, showing how it had evolved into distinct variants within different lineages of creatures, Brown and Doolittle compared the variants, constructing an independent tree of descent for each, This exercise yielded a telling point: the trees didn't match, The logical conclusion was that genes have their individual lineages of descent, not necessarily matchin gthe lineage of the organism in which they are presently found, As Robert Feldman said, "each gene has its own history, "

And so the tree of life has been redrawn, more as a weird, tangled shrub or "reticulated tree"In this New York Times bestseller and longlist nominee for the National Book Award, “our greatest living chronicler of the natural world” The New York Times, David Quammen explains how recent discoveries in molecular biology affect our understanding of evolution and lifes history.


In the mids, scientists began using DNA sequences to reexamine the history of all life, Perhaps the most startling discovery to come out of this new fieldthe study of lifes diversity and relatedness at the molecular levelis horizontal gene transfer HGT, or the movement of genes across species lines.
It turns out that HGT has been widespread and important we now know that roughly eight percent of the human genome arrived sideways by viral infectiona type of HGT,

In The Tangled Tree, “the grandest tale in biology, David Quammen presents the scienceand the scientists involvedwith patience, candor, and flair” Nature, We learn about the major players, such as Carl Woese, the most important littleknown biologist of the twentieth century Lynn Margulis, the notorious maverick whose wild ideas about “mosaic” creatures proved to be true and Tsutomu Wantanabe, who discovered that the scourge of antibioticresistant bacteria is a direct result of horizontal gene transfer, bringing the deep study of genome histories to bear on a global crisis in public health.


“David Quammen proves to be an immensely wellinformed guide to a complex story” The Wall Street Journal, In The Tangled Tree, he explains how molecular studies of evolution have brought startling recognitions about the tangled tree of lifeincluding where we humans fit upon it, Thanks to new technologies, we now have the ability to alter even our genetic compositionthrough sideways insertions, as nature has long been doing, “The Tangled Tree is a source of wonder, Quammen has written a deep and daring intellectual adventure” The Boston Globe, .