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Meet the ancestors: blobs of gelatinous goo that were some of the first animals on Earth.

The fossil traces have been discovered in Canadian rocks some 850 million years old – potentially solving a major problem for the origin of animal life.

And going back in time another two billion years, evidence of the earliest known cave-dwelling organisms are offering a glimpse of how life left the seas and conquered the continents.
Ancient traces

The previous oldest animal fossils date from “only” 650 million years ago, although “molecular clocks” based on rates of genetic divergence indicate that animals should have originated about 850 million years ago. The new findings may therefore help solve the problem of the 200 million-year-gap.

Palaeontologists have looked long and hard for traces left by the first multi-celled organisms, fully aware that the soft-bodies might have left very few fossils.

The breakthrough came when Elizabeth Turner, of Laurentian University in Sudbury, Ontario, spotted odd patterns in the rocks of 850-million-year-old limestone reefs in the Mackenzie Mountains of Canada’s Northwestern territory, and has spent the last 15 years, with Fritz Neuweiler of University Laval in Quebec, trying to deduce their origin.

Now Turner and Neuweiler, along with David Burdige of Old Dominion University in Virginia, have shown that the patterns match the distinctive textures found in reefs built by sponges.

‘Gelatinous goo’

Studies of modern sponges show that when their collagen structure decays it calcifies and leaves a signature pattern. Since collagen is a fibrous protein found only in animals, some ancestral animal must have lived in the ancient reef, they argue.

The animal consisted of “cells living embedded in a scaffold of collagen, which they extruded to make their home,” says Turner. “There probably were more than one type of cell, but we can’t tell.” Nothing like it lives today, but if we saw one it would look like “a little blob of gelatinous goo”, she says.

The presence of animals this early in Earth’s history would resolve the long-standing disparity between molecular clocks and the fossil record, and show that the evolution of animals began before the Earth slipped twice into a global deep freeze.

“I applaud the approach of looking for distinctive textures seen along with sponge skeletons in younger rocks,” says Andrew Knoll of Harvard University. “It’s a good first step, but it’s not yet proof.”
Cave life

Meanwhile evidence of Earth’s earliest cave dwellers offers a new glimpse of how life conquered the planet. Birger Rasmussen of the Curtin University of Technology, Western Australia, and colleagues report that complex microbial communities thrived in protective cavities on land as early as 2.75 billion years ago.

The discovery of the cavity-dwelling microbes challenges our view of where and how quickly life spread onto land and may have important implications for life on Mars, says Rasmussen. Although microbes have been flourishing in the oceans for about 3.5 billion years, the absence of oxygen and ozone to block ultraviolet radiation from the sun made the Earth’s surface a harsh environment until 2.4 billion years ago.

The only life that had been known to venture onto that surface were simple cyanobacteria (also known as blue-green algae) that during the last few hundred million years of that period formed mats and mounds mixed with sediment called stromatolites in shallow fresh water

Now Rasmussen has found these primitive land dwellers had company hiding under the surface – hiding in a complex subterranean ecosystem fed by chemical nutrients produced by other bacteria.

Mars too?

Microscopic examination reveals that millimetre-scale pillars of bacteria once lived in gas cavities trapped between layers of a 2.75-billion-year-old stromatolite, making them the oldest evidence of cavity dwellers by more than 1.5 billion years.

The microbes lived in cavities a centimetre or two high and up to 20 centimetres long, that were probably only centimetres beneath the surface – pressure would have flattened any cavities more than a metre down, says Rasmussen. But that was enough to protect the microbes from the harsh surface conditions.

Carbon and sulphur isotope levels indicate that some of the cavity-dwelling bacteria fed on methane bubbling up from lower levels of stromatolites, whilst others munched sulphur compounds, he says. The column shapes are complex and diverse, and resemble cavity-encrusting deposits formed by modern microbes.

Sub-surface micro-cavities may not only have been an important refuge on early Earth. They could have been even more important on Mars, where oceans were short lived and the atmosphere offered little protection, so conditions were not favourable for life to develop.

Today the Martian surface is inhospitable to life, but “micro-cavities are places on Mars where you might have conditions suitable for life currently,” but they would more likely have harboured life on ancient Mars, Rasmussen says.

We expect the prowess of our joints and lungs to slowly decline as we age, but the thought of our minds doing the same is intolerable. Here are some top prevention tips worth their weight in wits, plus a few to forget.

1. Do something!

Scientists are starting to think that regular aerobic exercise may be the single most important thing you can do for the long-term health of your brain. While the heart and lungs respond loudly to a sprint on the treadmill, the brain is quietly getting fitter with each step, too. For mental fitness, aim for at least 30 minutes of physical activity every other day.

2. Eat, eat, eat

Too much or too little energy throws a kink in the brain’s delicate machinery. A low glycemic diet — high fiber, with moderate amounts of fat and protein — is broken down more slowly in the body than high glycemic foods, such as sweets and white starches. A steady pace of digestion in the gut gives a more reliable flow of energy to the brain, likely optimizing the organ’s long-term health and performance.

3. Catch that diet

While overindulging can make the brain sluggish and lead to long-term detriments to your brain, too few calories can also impair brain function. Extreme dieting can cause some diehards to feel stretches of calm - a feeling that may underlie the addiction of anorexia — but many studies have also linked dieting with distraction, confusion and memory impairment.

4. Take care of your body

Largely preventable diseases - such as Type II diabetes, obesity and hypertension — all affect your brain, too. System-wide health concerns have been linked to an increased risk of cognitive decline and memory impairments. Keeping your circulatory system in working order, by, say, avoiding cigarettes and saturated fat, lessens the onslaught of age-related damage to the brain.

5. Get your beauty rest

When we rest and dream, memories are sifted through, some discarded, others consolidated and saved. When we don’t sleep, a recent study found, proteins build up on synapses, possibly making it hard to think and learn new things. Furthermore, chronically sleeping poorly (in contrast to not enough) is linked to cognitive decline in old age, although the relationship may not be causal.

6. Enjoy your coffee

Growing evidence suggests a caffeine habit may protect the brain. According to large longitudinal studies, two to four perk-me-ups a day may stave off normal cognitive decline and decrease the incidence of Alzheimer’s by 30 to 60 percent. It is unclear whether the benefits come from caffeine or the antioxidants found in coffee and tea, but that latte may improve cognition this afternoon and several decades from now.

7. Eat fish

Some theories credit the introduction of fish into the human diet with the evolution of our tremendous cognitive prowess. Essential fatty acids, such as Omega 3s, are critical to brain function and are proving beneficial for treating such brain-sapping ailments as depression. Studies on the efficacy of Omega 3 supplements, however, have had mixed results, so get doses from food sources, such as flax seeds, fatty fish and grass-fed animals.

8. Chill out

Stress takes a toll on the brain by washing harmful chemicals over the hippocampus and other brain areas involved in memory. Some scientists suspect that living a balanced lifestyle and pursuing relaxing activities such as yoga, socializing and crafting may delay memory impairment by reducing stress.

9. Skip the supplements

Supplements have been getting a bad rap recently, with even the familiar multivitamin now looking like a waste of money - or worse. Brain pills, such as ginkgo and melatonin, likely belong in the trash as well. Despite their “natural” origins, they are not free of potential side effects, such as high blood pressure, digestion trouble, fertility problems and depression. And among healthy individuals, ginkgo offers no brain benefits beyond that of a placebo. (In some cases, the placebo worked better.)

10. Tease your brain

Whether crossword puzzles, sudokus and other brain teasers actually keep your brain in shape, has not been well-established. However, lack of education is a strong predictor of cognitive decline. The more you’ve tried to learn, the better you’ll be at mental sit-ups in old age. The key may be tackling something new; the challenge of the unknown is likely more beneficial than putting together the same jigsaw puzzle over and over again.

Whether it’s penis size, papillomavirus risk, or profligate pregnancies, it’s good to know the numbers. Check out these stats to see if you are well within the sexual mean — or if you’re off the charts.

1. Are you infected?

At least 50 percent of sexually active men and women will have a genital HPV infection at some point in their lives. HPV, or human papillomavirus, comes in both low- and high-risk forms; low-risk HPV can cause genital warts, and high-risk can cause cervical and other cancers. In 90 percent of cases, the body’s immune system will fight off the disease within two years.

Source: Centers for Disease Control and Prevention

2. Did you take maternity leave?

Two-thirds of women who had their first baby between 2001 and 2003 worked during their pregnancy, and 80 percent of those women worked within one month or less of giving birth. Compare this to the period between 1961 and 1965, when 44 percent of women worked during their pregnancy (35 percent worked one month or less before delivering).

Source: U.S. Census

3. How many sex partners have you had?

What’s your number? According to a survey of adults aged 20 to 59, women have an average of four sex partners during their lifetime; men have an average of seven.

Source: National Center for Health Statistics

4. Do you get fringe benefits?

Two-thirds of college students have been in a “friends with benefits” relationship, citing the lack of commitment required as the main advantage to such an arrangement. More than half of those who had sex with a friend said they had engaged in all forms of sex; 22.7 percent said they had intercourse only, while 8 percent said they did everything but have intercourse.

Source: Wayne State University and Michigan State University

5. Do you reach orgasm every time?

While 75 percent of men always reach orgasm during sex, only 29 percent of women report the same. In addition, most women are unable to climax through vaginal intercourse, instead needing clitoral stimulation.

Source: National Health and Social Life Survey

6. Do you have a comfortable couch?

About one out of 10 married adults — 12 percent — say that they typically sleep alone.

Source: National Sleep Foundation

7. When did you lose your virginity?

The average male loses his virginity at age 16.9; females average slightly older, at 17.4. And a new study shows that genetics may be a factor: inherited traits, such as impulsivity, can make a person more or less willing to have sex at an earlier age.

Sources: Kinsey Institute; California State University

8. Do you need assistance?

Approximately 5 percent of 40-year-old men and between 15 to 25 percent of 65-year-old men experience erectile dysfunction.

Source: National Institute of Diabetes and Digestive and Kidney Diseases

9. Does size matter?

Relax, guys. No matter what those, ahem, movies might suggest, in the United States, the average erect penis is five to seven inches long, and four to six inches in circumference.

Source: Kinsey Institute

10. Why do you do it?

Sure, there’s the obvious. But there’s also an argument for men’s biological drive to perpetuate their genes: An 18th-century Russian woman holds the world record for having birthed the most children: 69, which she had over the course of 27 pregnancies that included sixteen pairs of twins, seven sets of triplets, and four sets of quadruplets. But she’s outdone by the male record-holder for most kids, a Moroccan emperor who, according to the Guinness Book of World Records, sired “at least 342 daughters and 525 sons, and by 1721, he was reputed to have 700 male descendants.”

Source: “Why Evolution Is True” (Viking, 2009), by Jerry Coyne