A sad cow

Eating Meat: Evolution, Patterns, and Consequences

This blog post is a sum­mary of Vaclav Smil's pa­per Eating Meat: Evolution, Patterns, and Consequences. Although I eat meat, it should be noted that I am not an ex­pert in meat. Thus, please take this sum­mary with a grain of salt.

As with any sci­en­tific ar­ti­cle, the in­for­ma­tion may be wrong or out of date. To note, this pa­per was pub­lished in 2002. Keep that in mind when I use words like currently.”


Humans evolved to eat meat–and thus we should in­clude at least some meat in our diet. Yet, meat isn't a re­quire­ment be­cause hu­mans can make up the needed nu­tri­tion from other sources.

We eat meat for more than just nu­tri­tional re­quire­ments. To this day, meat ac­qui­si­tion is still con­sid­ered a sign of suc­cess, and we share meat with oth­ers to cre­ate so­cial bonds.

The au­thor lays out an ul­ti­ma­tum: meat is not neu­tral. Some cul­tures have revered killing and eat­ing an­i­mals. Others, par­tic­u­larly re­li­gious aes­thet­ics, have ab­horred eat­ing meat.

Due to the way meat is pro­duced, a civ­i­liza­tion ob­sessed with meat puts it­self at risk for spread­ing dis­ease.

The West tends to limit the scope of what we mean by meat. For af­flu­ent coun­tries, it usu­ally only refers to the meat of do­mes­ti­cated mam­mals and birds.

Historically, hu­mans have con­sumed more than just pro­teinous mus­cle. Culture has got­ten pro­gres­sively more choosy over time about which parts of the an­i­mal are ac­cept­able to eat.

Fatty meats pro­vide more en­ergy and palata­bil­ity. This is par­tially why greasy fast food is ad­dict­ing–it's full of fat.

The au­thor con­cludes that af­flu­ent coun­tries are con­sum­ing too much meat. In a sense, hu­mans used to com­ple­ment their di­ets with meat. We now dom­i­nate our di­ets with meat.

Evolutionary heritage and preagricultural meat consumption

A long time ago, hu­mans learned how to use fire. The abil­ity to cook meat greatly in­creased an­cient hu­man­ity's meat-eat­ing op­por­tu­ni­ties.

Humans learned to kill large her­bi­vores be­cause they pro­vided a lot of fatty, en­ergy-dense meat. These her­bi­vores could be killed with­out us­ing weapons–just sim­ply drive them off a cliff.

The ori­gins of hu­man in­tel­li­gence are linked to meat. Cognitive abil­ity was likely needed for hu­mans to co­or­di­nate the shar­ing of meat within a group.

Humans have ab­nor­mally large brains. To sup­port the growth of this or­gan, it is hy­poth­e­sized that an­other or­gan had to be down­sized. Possibly, our gas­troin­testi­nal tracts were shrunk to give more meta­bolic en­ergy to the brain. With a smaller tract, an an­i­mal can't di­gest as ef­fec­tively. Thus, this change would have caused hu­mans to seek more en­ergy-dense food.

Different hu­man cul­tures ate dif­fer­ent amounts of meat, and thus there was a wide range of per-capita meat/​pro­tein in­takes. Meat in tra­di­tional agri­cul­tural so­ci­eties About 10,000 years ago, hu­mans learned how to farm. Farming food in­creased the pop­u­la­tion den­sity but si­mul­ta­ne­ously de­creased the av­er­age qual­ity of nu­tri­tion.

Even among rich European house­holds in the late 18th cen­tury, eat­ing meat was quite rare. Peasants may only have eaten meat 2 or 3 times a year.

Around the 1930s, meat sup­plied only around 2% of all food en­ergy.

Modern dietary transition and its outcomes

Diets started to change in Europe around the mid 19th cen­tury. Markedly, there was a dra­matic in­crease in meat con­sump­tion, which was dri­ven by the com­bined forces of im­proved agri­cul­tural pro­duc­tiv­ity, rapid in­dus­tri­al­iza­tion, and wide­spread ur­ban­iza­tion.

The pace of world­wide di­etary change in­creased af­ter World World II be­cause mech­a­nized agri­cul­ture was ag­gres­sively sub­si­dized.

The first re­frig­er­ated ship­ments of meat be­gan in the 1870s, which helped the ex­pan­sion of world­wide meat trade.

In the Western world, we mostly only eat beef, pork, or poul­try. The con­sump­tion of other meats has been steadily de­clin­ing over the years.

By the end of the 20th cen­tury, the pop­u­la­tion of af­flu­ent coun­tries rep­re­sented only one-fifth of the global to­tal but pro­duced and con­sumed two-fifths of all red meat and three-fifths of all poul­try.

To pro­duce more meat, hu­mans iron­i­cally need to pro­duce more grain to feed the an­i­mals. Thus, meat is not a per­fect sub­sti­tute for plants; they're com­ple­ments.

Animal feeding requirements

There is a trade­off when feed­ing grain crops to an­i­mals. For ex­am­ple, if food­grains were cul­ti­vated in­stead of feed crops, we would pro­duce more di­gestible en­ergy and pro­tein. Yet, an­i­mals pro­duce higher qual­ity pro­tein.

Cows suck at turn­ing feed grain into meat. They con­sume about 50% more en­ergy than pigs. Chickens are the best con­vert­ers of plant-to-an­i­mal pro­tein–at about 20% ef­fi­ciency.

Overall, the three ma­jor an­i­mals–cows, pigs, and chick­ens–are ex­tremely in­ef­fi­cient at cre­at­ing pro­tein. About 80 to 96% of plant pro­tein con­sumed is not con­verted to an­i­mal pro­tein.

Environmental consequences of meat production

Nowadays, hu­mans eat so much meat that do­mes­tic an­i­mals have be­come the dom­i­nant class of ver­te­brates on Earth. In sum­mary, there's a lot of cows.

With cur­rent crop yields and feed­ing prac­tices, the en­tire world can­not eat meat at the same rate as the af­flu­ent coun­tries. To achieve meat-eat­ing for all, we would need to make ad­vances in bio­engi­neer­ing.

The num­ber of feed crops fed to an­i­mals could feed ap­prox­i­mately 3 bil­lion ad­di­tional hu­mans. In a way, it's tempt­ing to try switch peo­ple to a mostly plant-based diet. The only prob­lem is that hu­mans like eat­ing meat and would be un­likely to change our diet pref­er­ences in mass.

One needs large amounts of wa­ter to raise an­i­mals and grow feed crops. Thus, meat/​grain trade can ben­e­fit coun­tries with scarce wa­ter re­sources. This sit­u­a­tion can po­ten­tially set up a com­par­a­tive ad­van­tage in trade for wa­ter-rich pro­duc­ers.

The main fac­tor lim­it­ing the size and den­sity of an­i­mal pro­duc­tion is our in­abil­ity to dis­pose of wastes ef­fec­tively.

Health implications of meat production and consumption

Most of the an­i­mals we eat are so­cial an­i­mals–and this leads to var­i­ous eth­i­cal dilem­mas. Modern farm­ing tech­niques don't ex­actly take good care of the an­i­mals.

Meatpacking is one of the most dan­ger­ous oc­cu­pa­tions in the coun­try. In 2000, about 25% of meat­pack­ing em­ploy­ees, or about 4 times the pri­vate in­dus­try av­er­age, had non­fa­tal in­juries or ill­ness. Serious in­juries oc­cur at about 5 times the pri­vate in­dus­try av­er­age.

Obesity in adults was sta­ble be­tween 1960 and 1980–at about 25% of the pop­u­la­tion. In the 1980s, this per­cent­age rose by 8 points. By the 1990s, every third adult in the United States was obese.

Many meals in the United States are high in fat. The au­thor blames beef's high lipid con­tent and our pref­er­ence for fast food.

We use more an­tibi­otics on an­i­mals than on hu­mans. This prac­tice could po­ten­tially lead to bac­te­ria gain­ing im­mu­nity to es­sen­tial an­tibi­otics.

Possible adjustments

During the last four decades, hu­mans have tripled our meat pro­duc­tion.

Over time, our di­ets have be­come less dis­ci­plined–which has gone hand-in-hand with obese peo­ple claim­ing to be vic­tims.

There is no sci­en­tif­i­cally de­fen­si­ble rea­son for strict veg­e­tar­i­an­ism. Conversely, there is no de­fen­si­ble rea­son for the amount of meat cur­rently pre­vail­ing in Western di­ets. These meaty di­ets do not make peo­ple health­ier or pro­long their lives.