Make Meat Special

Feeling carnivorous or vegetarian, or somewhere in-between?

Is it okay to be carnivorous? Is it natural (whatever that means)?

I asked these questions when I was a teenager, like many other people who love animals. For a while I half-heartedly courted vegetarianism as an ideal, but it would be hard for Mum to prepare separate meals for a lettuce-loafer. Grown-ups never replied to my questions, except with blank looks. I still think they are good questions.  Had I asked Aristotle’s pupil, the Father of Botany Theophrastus, he would have declared that eating animals is immoral, but I can’t fully agree. There are health concerns and spiritual reasons for becoming vegetarian, but it is not for everyone.

Rich man, Poor man

Meat used to be a luxury only the rich and powerful could afford. Royalty and noblemen kept hunting preserves and woe betide the peasant who turned poacher to put venison or rabbit on his family table. The greater the amount and variety of meat consumed the higher the status of the eater. On April 4, 1662, the diarist Samuel Pepys proudly recorded: “We had a fricassee of rabbits and chickens, a leg of mutton boiled, three carps in a dish, a great dish of a side of lamb, a dish or roasted pigeons, a dish of four lobsters, three tarts, a lamprey pie (a most rare pie), a dish of anchovies … to my great content.” This was not a banquet but a feast shared with a few friends, and it took a massacre to prepare.

Meat is no longer the privilege of the few, but still a luxury in many places. In the New Guinea Highlands friends subsist on sweet potatoes and other vegetables while pigs, their most valuable possessions, are reserved for eating at weddings and other special occasions. But where animals and birds are now raised for food industrially and the fishing industry can efficiently hoover whole shoals of fish, flesh has become plentiful, cheap, and ordinary. Then it is undervalued.

Carnivores and calories

Average Americans eat a half-pound of meat per day. That represents a larger fraction of protein and calories than eaten by bears, badgers and raccoons, which are all members of the order Carnivora.  Animal classification looks wonky when you consider that orders are defined by a trunk, hoof, blow-hole, egg-laying, brain size and opposable thumb. For carnivores, it’s the presence of butcher’s teeth that matters. Dracula apart, our dentition excludes us from the Carnivora, but neither is there an order called Vegetaria nor Omnivora which would fit us better. Taxonomy has no traction with the diet of our species.

Yards of gut

But you can tell if an animal is a true carnivore by looking in its mouth and along its gut. It will have:

  • long canines for grabbing prey and carnassial teeth for shearing meat
  • a gaping mouth and large throat for swallowing food unchewed
  • a large stomach with very acidic gastric juice for sterilizing raw meat
  • a relatively short small intestine
  • and a small colon

On the other hand, a strict herbivore will have:

  • small, stumpy canines and flattened, tightly-packed molars for chewing fiber
  • sideways movement of the jaws for chewing
  • an enzyme in saliva for starting to digest starch
  • a stomach of variable size with up to four chambers
  • less acidic gastric juice, especially in ungulates for allowing microbial fermentation
  • a long small intestine
  • a voluminous and baggy colon and cecum where cellulose is digested

The contrast is most obvious when guts are measured. The small intestine of carnivores is no more than three times as long as the body (head plus trunk), whereas in herbivores it is ten times the length. A short, simple tube is adequate for digesting meat, whereas cellulose takes much longer to break down to sugar available for absorption. Since the rabbit’s gut is not long enough for this process it swallows “soft pellets” as soon as they are evacuated from the rectum for a second pass through the system.

Our anatomy is closer to herbivores, though lacking the specialization in ungulates for a fiber-rich diet. We call ourselves omnivores because of a mixed diet, but frugivore is a more accurate rendering of our origin. Our early ancestors probably subsisted on tropical fruits and berries with some animal protein when available. Our primate cousins still enjoy the same. But when and how did we acquire a large appetite for flesh?

Paleo diet

Fred Flintstone was more carnivore than trail-mix muncher, although the opposite may be closer to reality in the deep past. There was more big game in Paleolithic times, some now extinct, but hunting with spears was inefficient and dangerous before bows and arrows were invented (maybe 60k years ago). Our diet was then plant-based. The controlled use of fire goes back further (most authorities estimate since 500k years ago), and cooking followed. Red meat was probably a rare meal before cooking was discovered because we are poorly equipped for eating and digesting it raw.

Early humans were of course locavores. As they fanned across the world, they had to adapt to unfamiliar local foods in different climates and environments. As the plant foods changed so did the animal populations they supported. Animal protein and fat came from fish, shellfish, bird eggs, and insects (yes!), supplying essential fatty acids and vitamin B12 before serious hunting was able to garner more meat and offal. Animal domestication arrived only around 400 generations ago and changed everything.

It is surely one of the mysteries of human evolution how our species was pre-adapted to subsist on a wide variety of diets, for without that flexibility our story would be different.

It should be no surprise that that herbivore can manage a meat meal. Chimpanzees do; after inquiries into the cause of mad cow disease we know that cows can too. But carnivores don’t have the specialized gut needed for tackling plant fiber, except in the world imagined by Isaiah where: “The lion shall eat straw like the ox.”

Our physiology is flexible but urges modest amounts of meat, if any. Being designed for fruits and green leaves, our stomachs are not sufficiently acidic to kill Salmonella and other bugs in raw meat. And when the diet is rich in protein, and particularly purines, our lack of an active uricase gene can lead to painful joints if uric acid crystals accumulate. Carnivorous animals have active copies of the gene, so it is surprisingly that “Sue”, a T. rex from Cheyenne River Indian Reservation, had a touch of gout.

I guess that meat-eating was a necessary adjustment when people migrated to northern lands. Seasonally abundant vegetables disappeared in winter whereas most native wildlife remained, and some were good to eat. Much later, herds of sheep, goats and reindeer provided more food security than by hunting, although further north nomads depended on meat and blubber from marine mammals.

The modern paleo diet claims to bring food choices in line with our genes, which are assumed to have changed little since Paleolithic times. But there was no standard caveman diet across the world, and contemporary hunter-gatherers in Africa and South America eat only what they can catch, according to where they live. Besides, a standard can’t be offered without a matching lifestyle and age span. Early humans have to live strenuously to survive, and few lived to what we now call middle age. Backers of the paleo diet can’t insist on those changes. Some plants eaten in the past have come down to us as crops but they have been genetically altered by selective breeding or even genetic modification, and the microbes in our guts have probably changed too.

It’s a fallacy to believe we can copy the nutrition from bygone eras, but a more cogent reason for rejecting the paleo diet is that it aggravates the environment by reinforcing or even promoting more meat consumption.

The Price of Meat

MeatongrillIn a world of soaring population where 30 % of usable land is already devoted either directly or indirectly to raising livestock the meat industry is on an unsustainable trajectory. Our appetite for red meat impacts virgin rainforests which are converted to ranches, production of greenhouse gases, vast subsidized cornfields, water consumption and pollution, and antibiotic abuse for animals confined to feedlots. Cattle are not the only species to beef about, but the growing middle class in Asia has a greater appetite for white meat which is produced more efficiently. Fish farming helps to relieve pressure from ocean harvests, although not without its own problems.

Our ability to produce ever larger quantities of animal protein will finally be capped by the carrying capacity of the environment and the unchallengeable Laws of Thermodynamics. The problem is illustrated by a pyramid representing an ecosystem where energy is transferred from bottom to top by a thermodynamic “hand-shake:”

  1. At the base plants absorb solar energy for growing
  2. Herbivores occupy an intermediate level where they gain energy from plants
  3. Carnivores on top of the pyramid dine on herbivores below

The biomass diminishes sharply higher up because energy is transferred between levels with only 10% efficiency.  Sometimes, there is a fourth level of super-carnivores (sharks, tuna, and T. rex) feeding on lower carnivores, but there can be no more because less than 0.01% of the original energy remains.

We don’t eat carnivores because they are relatively rare and considered unpalatable. But herbivores taste good to us, and we eat lots of them. There are perhaps 1.5 billion cattle in the world today, and countless other beasts and birds farmed for meat. But if crops grown to feed animals were switched for direct human consumption much larger numbers of people could receive their daily ration of 2,000 Calories.

For example, the 10% rule-of-thumb predicts that 20,000 Calories of corn has a net yield of only 2,000 Calories of cow because most energy is lost. The same amount of corn could support several people, though perhaps not quite as many as ten. Beef has higher quality protein than in corn, but the example stands an argument for swaying food choices and policy. One government actually took a swipe at national food consumption.

Less is More

In World War Two, German U-boats blockaded shipments of food from North America to British ports triggering a fear of hunger because the country was not self-sufficient in food. The British Government secretly commissioned two Cambridge nutritionists to find out how many home-grown Brussel sprouts and sausages the public needed to keep in good health (no Bratwurst, only patriotic British sausages.)

Elsie Widdowson and Robert McCance fed subjects in their clinical trial 1 lb of meat, 1 egg, and 4 oz of fish per week, plus 5 fluid oz of milk a day, and unlimited amounts of vegetables and wholemeal bread, which together would meet dietary requirements. After the subjects w remained in excellent health months later, the meager rations were rolled out as government policy with only a fraction of the meat consumed in Britain today. Family health was said never to be better; infant mortality fell and life expectancy rose (discounting deaths from hostilities), and the only downside was a “remarkable” increase in flatulence.

Since then, Britons have been eating more and more meat, following the prosperous example of America. There are plenty of sound reasons for cutting back on meat consumption, and some people are, but short of a national catastrophe or an environmental calamity policy-makers won’t go further than offering bland health advisories. The only other potential check on growth is the market, and producers won’t forgo sales while demand exists. So it remains for individuals to make up their own minds and hope to make a difference.

Cutting back may be the first step to cutting out, but often the hardest to make. A trade-off can make a step easier, and there is none better than trading quantity for quality. They generally pull in opposite directions. Forcing the productivity of farm animals, like the breeding of high-yielding fruit and vegetables, pleases shoppers by lowering prices but comes at a cost. The cost is mainly elsewhere and unseen (on land and water), but we notice differences in flavor, and wonder if the host of biochemical differences have consequences for our health.

Away then with factory farming, away with corn feedlots. Bring back more grass-fed beef; bring back pastured chickens and eggs from happier animals; bring back flavors that old-timers still remember.

It would help if instead of casually tossing packs of steak, pork or chicken in our trolley as mundane shopping, we remember that meat is special. It costs the earth more, and it demands the sacrifice of animal lives. Eating less but better seems an excellent exchange for the half-pound steak that never inspired any note in a diary. Samuel Pepys was inspired to celebrate tasty food, but he might have curbed the temptation to eat to excess had he known it contributed to his gout.

But cutting back seems to run counter to the America tradition as a land of plenty where self-denial can appear eccentric. A 16 oz steak, or even a Flintstone-sized 32 oz, is emblematic of that life, but maybe carnivores can be satisfied with less. I dream of a new Marlboro ad on a billboard showing a man standing beside a barbecue grill, beckoning to us, “Come to Where the Flavor Is.” Outsized steaks have been vaped. He turns over with his fork a smoking nugget of grass-fed beef.

Next Post:  Virginia Nature Journal for May

Virginia Nature Journal for April

Algernon Swinburne

Smells arouse old memories, good and bad. The coconut bouquet of prickly gorse bushes evokes memories of ranks of jasmine blossom on the chalky downs of the Isle of Wight where I was born and Algy Swinburne grew up. Oh, to be in England, now that April’s there (Robert Browning). But here in Tidewater Virginia, the scent of pine resin at this season conveys no particular emotion for me, nor can it trigger flashbacks.

Crabapple tree blooming in April
Crabapple tree blooming in April

I read that memory is less aroused by sound than by smell which owes its potency to a handshake between our olfactory bulbs and the hippocampus. But when I hear the lazy phrases of a blackbird, my mind is transported to a remembered English garden where one sang every afternoon announcing its territory from a perch in apple blossom. But here, where brown thrashers, wood thrushes and mocking birds are better musicians, the chorus of woodland songsters never evokes the same emotion, perhaps because some neural networks close after childhood.

And yet less emotion does not mean less care for the birds that choose to make a home in our yard. In a landscape where native plants of Virginia are retreating before the advance of so many inedible aliens, they need us when food supplies reach a nadir. The bird feeder was not full for very long and never empty during the winter. Long before our neighborhood birds started looking for nesting sites I made a batch of boxes for them, one for every acre. They are luxury condos made of durable white cedar with green shingle roofs and a critter-guard against snakes, raccoons and squirrels.

WelcomeEggs_smallThe boxes were designed for bluebirds, which are surely in the top ten for popularity. Cavity nesters depend on these artificial homes because cautious park officers and yard owners fell dead trees which might have offered them a home. Apart from untold numbers of nest-boxes in gardens, there are 230 boxes around public trails and golf courses in James City and York counties that are monitored weekly by local naturalists. It is exciting to find a clutch of 4 or 5 bluebird eggs (sky blue, of course), and experts assure us that a brief inspection does not affect breeding success.

The program has reversed the steady decline in their population, and now there are more bluebirds in the area than at any time in living memory. Over 700 of them fledged from these boxes alone last year. The Virginia Bluebird Society collects breeding data from across the state, and at summer’s end we will know what impact the hard winter had on their population.

Chickadee nesting in bluebird box
Chickadee nesting in bluebird box

There were bluebirds in our yard until the deep freeze started in February, but we saw few afterwards. There are reports of birds found dead in nest-boxes where they were roosting. Drinking water was frozen for several weeks, and there were few berries or other natural foods at the end of winter. Perhaps the hard weather explains why a chickadee took up residence in one of our bluebird boxes, a tufted titmouse in another, and Carolina wren is building a nest in a third. One box is vacant where a pair of bluebirds raised two broods last year.

Bluebird laying recordBluebirds are nesting elsewhere, but they started late this year, although no later than in the past two years. Our records for 2012-15 suggest their breeding schedule is flexible, so that hungry fledglings are not hatched before insects are abundant again. In the warm spring of 2012, the first eggs were laid three weeks early.

The great horned owls breeding on Jamestown Island don’t have to be respecters of temperature and weather because their prey is ever present. They were sitting on eggs in January, and their owlets were almost ready to fly when the bluebirds were starting to gather straw and down to line their nests.

Red-shouldered hawk on nest
Red-shouldered hawk on nest

Besides the vagaries of weather, bluebirds face the daily challenge of evading predators. They have little to fear from nocturnal species like owls, but a pair of red-shouldered hawks has taken up residence in our woodlot, and I guess they have chicks sitting on the untidy matt of sticks in the fork of a loblolly pine. Their breeding schedule coincides with the re-appearance of frogs and reptiles and when baby rodents set foot out of the nest and naïve baby birds flutter out of theirs. We hear the hawks screaming kee-rah all day long to scare birds out of cover or before taking a dive at them on the bird feeder. I feel no special sympathy for an English sparrow in yellow talons, but there would be a rush of emotion if I noticed a splash of blue on prey feathers.

Next Post: Cuisine for Carnivores


GM Human Eggs Have Arrived

We heard confirmation last week of rumors that scientists at Sun Yat-sen University in southern China were trying to change the DNA of freshly-fertilized human eggs. This “first” in science was greeted with horror, hand-wringing, and a storm of criticism. Why the fuss?

They were testing a new technique in abnormal embryos donated to research by an in vitro lab. Their goal was to avoid a common, heritable disease by correcting a faulty gene. The target was the beta-globin gene because it codes for oxygen-carrying hemoglobin, but causes beta-thalassemia when it is mutated. Four per cent of people in south-east Asia have one or two copies of this mutation; over 55,000 affected babies are born with beta-thalassemia every year worldwide. Those babies die without monthly transfusions of matched blood or a bone marrow transplant, if they can get them.

Curing this genetic scourge would be a big deal. First, it would break mutations from cycling through the generations of affected families, although treatment will never eliminate the sporadic risk of a fresh mutation. Second, a breakthrough could be a model for challenging other genetic diseases, especially when the fault is confined to a single locus.

If this background sounds so positive and worthwhile, why is it excoriated instead of celebrated as a life-saving technology?

The news was a déjá vu moment for me. While working in Edinburgh in the 1990s, I was seized by a controversy over ovarian transplants while colleagues who cloned Dolly the sheep across town were caught up in a media whirlwind. The language used to describe those efforts was the same as in current media reports and interviews, seasoned with bogey-words like Playing God, Dr. Frankenstein, Gattaca, eugenics, slippery slope, GM designer babies, genetically-engineered human race, etc.

I presume the Chinese researchers were not motivated by those nightmares, but focused on the hope of curing a dreaded disease. There are, of course, plenty of examples where a discovery has had unintended consequences, including radioactivity and DNA itself. We are still juggling with their consequences, but few will deny the net benefits, and we can never turn the clock back to un-discover something that is abused. Admittedly, when genetically-modified (GM) humans are conceived in the future by so-called germline modification, biomedicine will cross a Rubicon because changes in the DNA of a fertilized egg are inherited by every cell in the body, including the gametes which pass the changes down to children and to children’s children. When that happens, our species will begin evolving on a self-determined path and bioethics will face its sternest moment.

Meanwhile, a debate boils over a study that made such a small contribution to knowledge that it was rejected by two top journals. The media hype will no doubt rouse some hastily scrawled letters to Members of Congress urging them to stop mad scientists! Congress, of course, has no powers over foreign research and federal regulation of American labs (one at least is reportedly engaged in similar research) is highly unlikely because we still don’t have laws for regulating in vitro labs (although federal funds for human embryo research are banned). In hindsight, the uproar we experienced in the 1990s was wasted heat, because ovarian transplants now enable former cancer patients to conceive healthy babies naturally and the prospects of cloning human babies are still remote.

For many years, GM or “transgenic” mice have been engineered using a complex, transgenerational process to introduce or remove harmful mutations. But that technology could never be applied in humans, as I explained in Designing Babies: the Brave New World of Reproductive Technology (1999):

“Nowadays, extremely precise genetic changes can be made in the laboratory. Every week we hear about mice that have been given a gene before birth to replace a defective one or have had another one knocked out by a mutation to see what will happen. Many people have heard about the famous “oncomouse” which develops cancer after an induced genetic change, though most heritable changes are not so adverse. Immense benefits are flowing from this technology as it provides a better understanding of how diseases develop and can best be treated … experiments with mice have shown that it is possible to reverse a natural mutation by introducing a correct copy of the genetic flaw to make the mouse completely well. There are many such revealing examples of genetic engineering in animals. If these changes can be made so accurately in a mouse, why not in a human too?” (page 121)

The Chinese researchers have answered me using a new gene editing tool called CRISPR/Cas9, which was discovered as a defense against viral infections in bacteria. CRISPR/Cas9 is a molecular duplex consisting of a targeting and a cutting module, and this toolkit has been adapted for deleting or replacing short segments of DNA in mouse embryos, human cell cultures, and now human eggs. It works like a programmable search engine to locate a highly specific sequence of DNA letters in the genome for cutting out and splicing in new letters. It is remarkably precise and so simple to use that staff of in vitro labs have the training and apparatus to try it. That is a concern.

in vitro fertilization
Healthy human egg with two pronuclei (marked)
Courtesy: Lucinda Veeck Gosden

This first trial of CRISPR/Cas9 in human eggs mostly failed to make the prescribed changes in the genome, but created alarming numbers of unintended or “off-target” mutations that might put future health at risk. Perhaps the results would have been better if healthy eggs been used instead of abnormal ones that were fertilized with two sperm. For a study that generated no significant advance in knowledge it stirred a lot of controversy, and the paper concluded with one of the great understatements of the year: “clinical applications … may be premature at this stage”

Do we need this technology? A few years ago when I was a visiting professor at Sun Yat-sen University one of my Chinese associates was developing an alternative technology called preimplantation genetic diagnosis (P.G.D.), which tests for genes for beta-thalassemia in embryo. This is now widely accepted by couples planning a family, and genetic modification has no place in it.

P.G.D. was originally introduced for screening other mutations, when it was roundly condemned as the road to designer babies with superior brains, beauty, and brawn! Some critics misunderstood the limitations of selecting for those kinds of desirable traits from the very small number of fertilized eggs available when couples undergo in vitro treatment. Here’s the rub—it’s great for those who can afford it because treatment is expensive, but unlikely to be more costly than when we can correct mutations in eggs.

Far more exciting and much less controversial applications of CRISPR/Cas9 technology to gene therapy have been overlooked in the recent fuss. Bad news and horror stories grab most attention from the media. After years of disappointing trials and a few serious upsets, there are fresh prospects for gene therapy for a wide range of inherited diseases and cancer, and even for agriculture. There is no ethical impasse because future generations are not committed to a man-made genetic change since eggs or sperm in patients are unaffected by treatment, although P.G.D. will be needed to safeguard health of future children. With gene therapy for all ages and P.G.D. to break disease cycling through generations of families, the argument for germline modification is stretched.

Nevertheless, true believers will endeavor to create a safe and effective technology for fertilized eggs, and, provided ethical standards are upheld, why shouldn’t they use discarded cells that can never create a human being? Besides, shouldn’t we admit that public attitudes and ethics shift, or wonder if future generations will mock us if we banned a field of basic research? In mid-Victorian times, anesthesia was sometimes denied to women in labor for theological reasons, and only in recent years has in vitro fertilization become accepted as a standard treatment for infertility. Who can predict the brave new future for humanity, except that it will be very different to present?

“The future is biology, of course. Everybody thinks the future is the computer, but the future is really the gene, the nucleus, the egg, and the embryo. And do you know why? Because all you can do is improve the computer. But you can really f*** with biology. I mean you wouldn’t believe what biology will withstand. You wouldn’t believe what you can do to it, and then what you have to do to it, because you can, because you have biology’s permission.” (Tom Junod in Esquire magazine in 1998)

There will be more condemnation of the Chinese experiments. We will see hubris from a few scientists claiming a medical revolution is at stake, and perhaps some crazy doctors craving attention will make false claims that GM babies have already been born, as they once did about cloned babies. Such a furor discourages responsible researchers from entering the field and will possibly send others underground or overseas where regulations are less stringent. Until more people realize that this research is still in its early infancy and GM babies are unlikely in our time, the theatre will continue and bioethicists will enjoy full-employment.

Next Post: Virginia Nature Journal for April