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Possible habitat for life on Enceladus, a moon of Saturn
– This graphic illustrates how Cassini scientists think water interacts with rock at the bottom of the ocean of Saturn’s icy moon Enceladus, producing hydrogen gas. Credit: NASA/JPL-Caltech
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Two veteran NASA missions are providing new details about icy, ocean-bearing moons of Jupiter and Saturn, further heightening the scientific interest of these and other “ocean worlds” in our solar system and beyond. The findings are presented in papers published Thursday by researchers with NASA’s Cassini mission to Saturn and Hubble Space Telescope.
In the papers, Cassini scientists announce that a form of chemical energy that life can feed on appears to exist on Saturn’s moon Enceladus, and Hubble researchers report additional evidence of plumes erupting from Jupiter’s moon Europa.
“This is the closest we’ve come, so far, to identifying a place with some of the ingredients needed for a habitable environment,” said Thomas Zurbuchen, associate administrator for NASA’s Science Mission Directorate at Headquarters in Washington. ”These results demonstrate the interconnected nature of NASA’s science missions that are getting us closer to answering whether we are indeed alone or not.”
The paper from researchers with the Cassini mission, published in the journal Science, indicates hydrogen gas, which could potentially provide a chemical energy source for life, is pouring into the subsurface ocean of Enceladus from hydrothermal activity on the seafloor.
The presence of ample hydrogen in the moon’s ocean means that microbes – if any exist there – could use it to obtain energy by combining the hydrogen with carbon dioxide dissolved in the water. This chemical reaction, known as “methanogenesis” because it produces methane as a byproduct, is at the root of the tree of life on Earth, and could even have been critical to the origin of life on our planet.
Life as we know it requires three primary ingredients: liquid water; a source of energy for metabolism; and the right chemical ingredients, primarily carbon, hydrogen, nitrogen, oxygen, phosphorus and sulfur.
With this finding, Cassini has shown that Enceladus – a small, icy moon a billion miles farther from the sun than Earth – has nearly all of these ingredients for habitability. Cassini has not yet shown phosphorus and sulfur are present in the ocean, but scientists suspect them to be, since the rocky core of Enceladus is thought to be chemically similar to meteorites that contain the two elements.
“Confirmation that the chemical energy for life exists within the ocean of a small moon of Saturn is an important milestone in our search for habitable worlds beyond Earth,” said Linda Spilker, Cassini project scientist at NASA’s Jet Propulsion Laboratory in Pasadena, California.
The Cassini spacecraft detected the hydrogen in the plume of gas and icy material spraying from Enceladus during its last, and deepest, dive through the plume on Oct. 28, 2015. Cassini also sampled the plume’s composition during flybys earlier in the mission. From these observations scientists have determined that nearly 98 percent of the gas in the plume is water, about 1 percent is hydrogen and the rest is a mixture of other molecules including carbon dioxide, methane and ammonia.
The measurement was made using Cassini’s Ion and Neutral Mass Spectrometer (INMS) instrument, which sniffs gases to determine their composition. INMS was designed to sample the upper atmosphere of Saturn’s moon Titan. After Cassini’s surprising discovery of a towering plume of icy spray in 2005, emanating from hot cracks near the south pole, scientists turned its detectors toward the small moon.
Cassini wasn’t designed to detect signs of life in the Enceladus plume – indeed, scientists didn’t know the plume existed until after the spacecraft arrived at Saturn.
“Although we can’t detect life, we’ve found that there’s a food source there for it. It would be like a candy store for microbes,” said Hunter Waite, lead author of the Cassini study.
The new findings are an independent line of evidence that hydrothermal activity is taking place in the Enceladus ocean. Previous results, published in March 2015, suggested hot water is interacting with rock beneath the sea; the new findings support that conclusion and add that the rock appears to be reacting chemically to produce the hydrogen.
Genetic variation, classification and race
Genetic variation, classification and ‘race’
Lynn B Jorde & Stephen P Wooding
Department of Human Genetics, University of Utah School of Medicine, Salt Lake City, Utah 84112, USA
Nature Genetics 36, S28 – S33 (2004) Published online: ; | doi:10.1038/ng1435
New genetic data has enabled scientists to re-examine the relationship between human genetic variation and ‘race’. We review the results of genetic analyses that show that human genetic variation is geographically structured, in accord with historical patterns of gene flow and genetic drift.
Analysis of many loci now yields reasonably accurate estimates of genetic similarity among individuals, rather than populations. Clustering of individuals is correlated with geographic origin or ancestry. These clusters are also correlated with some traditional concepts of race, but the correlations are imperfect because genetic variation tends to be distributed in a continuous, overlapping fashion among populations. Therefore, ancestry, or even race, may in some cases prove useful in the biomedical setting, but direct assessment of disease-related genetic variation will ultimately yield more accurate and beneficial information.
Figure 1: A neighbor-joining network of population similarities, based on the frequencies of 100 Alu insertion polymorphisms.
The network is rooted using a hypothetical ancestral group that lacks the Alu insertions at each locus. Bootstrap values are shown (as percentages) for main internal branches. (Because of the relatively small sample sizes of some individual populations, bootstrap values for terminal branches within main groups are usually smaller than those of the main branches, indicating less statistical support for terminal branches.)
The population groups and their sample sizes are as follows:
Africans (152): Alur, 12; Biaka Pygmy, 5; Hema, 18; Coriell Mbuti Pygmy, 5; a second sample of Mbuti Pygmy from the Democratic Republic of the Congo, 33; Nande, 17; Nguni, 14; Sotho/Tswana, 22; Kung (San), 15; Tsonga, 14. East Asians (61):
Cambodian, 12; Chinese, 17; Japanese, 17; Malay, 6; Vietnamese, 9. Europeans (118): northern Europeans, 68; French, 20; Poles, 10; Finns, 20. South Indians (365): upper caste Brahmin, Kshatriya and Vysya, 81; middle caste Kapu and Yadava, 111; lower caste Relli, Mala and Madiga, 74; tribal Irula, Khonda Dora, Maria Gond and Santal, 99.
Figure 2
A neighbor-joining tree of individual similarities, based on 60 STR polymorphisms, 100 Alu insertion polymorphisms, and 30 restriction site polymorphisms.
The percentage of shared alleles was calculated for all possible pairs of individuals, and a neighbor-joining tree was formulated using the PHYLIP software package. African individuals are shown in blue, European individuals in green and Asian individuals in orange.
Figure 3
(a) Results of applying the structure program to 100 Alu insertion polymorphisms typed in 107 sub-Saharan Africans, 67 East Asians and 81 Europeans. Individuals are shown as dots in the diagram.
Three clusters appear in this diagram; a cluster membership posterior probability of 100% would place an individual at an extreme corner of the diagram.
(b) A second application of the structure program, using the individuals shown in a as well as 263 members of caste populations from South India. Adapted from ref. 32.
Figure 4
A neighbor-joining tree formulated using the same methods as in Figure 2, based on polymorphisms in the 14.4-kb gene AGT.
A total of 246 sequence variants, including 100 singletons, were observed. The 368 European, Asian and African individuals are described further in ref. 54.
Author’s conclusion: “Race remains an inflammatory issue, both socially and scientifically. Fortunately, modern human genetics can deliver the salutary message that human populations share most of their genetic variation and that there is no scientific support for the concept that human populations are discrete, nonoverlapping entities.
Furthermore, by offering the means to assess disease-related variation at the individual level, new genetic technologies may eventually render race largely irrelevant in the clinical setting. Thus, genetics can and should be an important tool in helping to both illuminate and defuse the race issue.”
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Note by RK about -> ” there is no scientific support for the concept that human populations are discrete, nonoverlapping entities.”
– Outside of racist groups, no scientist even makes such a claim. This article does not debunk the idea that biological groups for humans exists: It clearly shows that such groups exist, in precise detail. However, this data debunk claims made from people using non-scientific definitions of words.
When scientists use words like “race”, “population” or “clade”, these words need to have precise meanings. Every discovery in biology and evolution over the last 200 years shows that biological groups has to exist. That is to say, all life has a family tree that can be represented by cladograms. Those cladograms show evolutionary phylogenies.
“A clade is a grouping that includes a common ancestor and all the descendants (living and extinct) of that ancestor. Using a phylogeny, it is easy to tell if a group of lineages forms a clade. Imagine clipping a single branch off the phylogeny — all of the organisms on that pruned branch make up a clade.”
See Clades and phylogenies and clades rotate = equivalent phylogenies.
Related articles
The Importance of Race and Ethnic Background in Biomedical Research and Clinical Practice
The New England Journal of Medicine, Vol. 348, p. 1170-1175, 2003
Esteban González Burchard, M.D., Elad Ziv, M.D., Natasha Coyle, Ph.D., Scarlett Lin Gomez, Ph.D., Hua Tang, Ph.D., Andrew J. Karter, Ph.D., Joanna L. Mountain, Ph.D., Eliseo J. Pérez-Stable, M.D., Dean Sheppard, M.D., and Neil Risch, Ph.D.
The Genomic Challenge to the Social Construction of Race
By Jiannbin Lee Shiao, Thomas Bode, Amber Beyer et al, Sociological Theory, Vol 30, Issue 2, 2012
Race in biology, genetics and cladistics. Wikipedia.
The Whole Side of It—An Interview with Neil Risch. By Jane Gitschier
Science of Jurassic Park
Jurassic Park is a 1993 film directed by Steven Spielberg. The first installment of the Jurassic Park franchise, it is based on the 1990 novel of the same name by Michael Crichton.
Next Generation Science Standards: Science & Engineering Practices
● Ask questions that arise from careful observation of phenomena, or unexpected results, to clarify and/or seek additional information.
● Ask questions that arise from examining models or a theory, to clarify and/or seek additional information and relationships.
● Evaluate a question to determine if it is testable and relevant.
● Ask and/or evaluate questions that challenge the premise(s) of an argument, the interpretation of a data set, or the suitability of the design
Science and engineering practices: NSTA National Science Teacher Association
Next Gen Science Standards Appendix F: Science and engineering practices
1. When did dinosaurs live? Investigate the geological eras.
Another view of the relationship between geological eras and the Earth’s strata.
2. What are chromosomes/genes/DNA nucleotides?
DNA is like an alphabet: Analogies to explain nucleotides, genes and chromosomes
3. How might DNA possibly be preserved for long periods of time?
4. What is the scientific premise of the film: How did they recreate ancient dinosaurs? Did they (according to the film) create dinosaurs at all?
5. According to the book & film, not enough intact DNA was recovered to create a true dinosaur. How then were the theme park dinosaurs created?
http://jurassicpark.wikia.com/wiki/Filling_the_sequence_gaps
6. Have scientists ever actually discovered preserved soft tissue, and/or protein, in dinosaur fossils?
http://www.livescience.com/41537-t-rex-soft-tissue.html
http://www.smithsonianmag.com/science-nature/dinosaur-shocker-115306469/?no-ist
https://student.societyforscience.org/article/more-dinosaur-bones-yield-traces-blood-soft-tissue
7. Have scientists ever actually discovered preserved DNA in dinosaur fossils?
http://www.livescience.com/23861-fossil-dna-half-life.html
http://www.sci-news.com/paleontology/science-dinosaur-dna-amber-01383.html
http://scitechdaily.com/researchers-calculate-that-dna-has-a-521-year-half-life/
http://www.nature.com/news/dna-has-a-521-year-half-life-1.11555
https://en.wikipedia.org/wiki/Ancient_DNA
8. Some scientists have proposed that we can realistically reverse engineer dinosaurs from living birds. What is their biological, and evolutionary reasoning for why this could make sense?
http://www.livescience.com/17642-chickenosaurus-jack-horner-create-dinosaur.html
Can Scientists Turn Birds Back Into Dinosaur Ancestors? National Geographic
TED Talks: Jack Horner on building a dinosaur from a chicken
9. How would these scientists actually go about doing this? (Summarize in a clearly written paragraph, describing several steps.)
Additional resources
Are Movies Science? DINOSAURS, MOVIES, AND REALITY Univ. of California Museum of Paleontology
Real-Life ‘Jurassic World’ Dinos May Be Possible, Scientist Says: LiveScience
Can scientists clone dinosaurs? How Stuff Works
Scrappy Fossils Yield Possible Dinosaur Blood Cells: National Geographic
DNA has a 521-year half-life, Nature (scientific journal)
The final nail in the Jurassic Park coffin. Research just published in the journal The Public Library of Science ONE (PLOS ONE)
Absence of Ancient DNA in Sub-Fossil Insect Inclusions Preserved in ‘Anthropocene’ Colombian Copal. (scientific journal)
Science of Jurassic Park: JurassicWikia
Book: The Science of Jurassic Park: And the Lost World Or, How to Build a Dinosaur
Are we consuming too little salt?
…Cutting back on salt can reduce blood pressure, but often, the change in blood pressure is small. According to the American Heart Association, a person who reduces salt intake from median levels (around 3,400 milligrams ) to the federal recommended levels (no more than 2,300 mg) typically sees a slight drop of 1% to 2% in blood pressure, on average.
Also, other factors affect blood pressure. For example, blood pressure increases with weight gain and decreases with weight loss. So, keeping a healthy weight can help prevent high blood pressure. Eating foods high in potassium also seems to counter some of the effects of high salt consumption on blood pressure.
Studies comparing salt intake in different countries worldwide have not found a clear connection between salt intake and high blood pressure. Societies that eat lower levels of salt do not necessarily have less heart disease than those that eat a lot of salt.
…Surprisingly little is known about how much salt we need. U.S. residents consume, on average, about 3,400 milligrams of salt per day. For decades, the U.S. government and organizations, such as the American Heart Association, have recommended people consume less salt. Current dietary guidelines recommend no more than 2,300 mg of sodium—about a teaspoon of salt—per day for teens and adults. No more than 1,500 mg per day is recommended for groups at higher risk of heart disease, including African Americans and everyone over the age of 50.
The U.S. dietary guidelines were established in the 1970s when relatively little information was available about dietary salt and health. The guidelines were the best guess, given the information available at the time. …
Some scientists now say that the average amount of salt U.S. residents eat (3,400 mg of salt per day) is safe and may even be healthier than the lower government guidelines.
In fact, a study found that people who meet the U.S. recommended limits for salt (2,300 mg of sodium per day) have more heart trouble than those consuming more salt. This study included approximately 150,000 people from 17 countries and was published in the New England Journal of Medicine.
Scientists challenging the current guidelines say people should consume at least 3,000 mg of salt per day and up to 6,000 mg per day. The new research results suggest a low-sodium diet may stimulate the production of renin, an enzyme released by the kidneys. Renin plays a role in regulating the body’s water balance and blood pressure. Too much renin may harm blood vessels, and a high-sodium diet would help lower the amount of renin produced….
KaiserScience 