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As with any sci¬≠en¬≠tiÔ¨Āc ar¬≠ti¬≠cle, the in¬≠for¬≠ma¬≠tion may be wrong or out of date. To note, this pa¬≠per was pub¬≠lished in 2002. Keep that in mind when I use words like ‚Äúcurrently.‚ÄĚ


Humans evolved to eat meat‚Äďand thus we should in¬≠clude at least some meat in our diet. Yet, meat is¬≠n‚Äôt a re¬≠quire¬≠ment be¬≠cause hu¬≠mans can make up the needed nu¬≠tri¬≠tion 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 af¬≠Ô¨āu¬≠ent coun¬≠tries, it usu¬≠ally only refers to the meat of do¬≠mes¬≠ti¬≠cated mam¬≠mals 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 pro¬≠vide more en¬≠ergy and palata¬≠bil¬≠ity. This is par¬≠tially why greasy fast food is ad¬≠dict¬≠ing‚Äďit‚Äôs full of fat.

The au¬≠thor con¬≠cludes that af¬≠Ô¨āu¬≠ent coun¬≠tries are con¬≠sum¬≠ing too much meat. In a sense, hu¬≠mans used to com¬≠ple¬≠ment their di¬≠ets with meat. We now dom¬≠i¬≠nate our di¬≠ets with meat.

Evolutionary heritage and preagricultural meat consumption

A long time ago, hu¬≠mans learned how to use Ô¨Āre. The abil¬≠ity to cook meat greatly in¬≠creased an¬≠cient hu¬≠man¬≠i¬≠ty‚Äôs meat-eat¬≠ing op¬≠por¬≠tu¬≠ni¬≠ties.

Humans learned to kill large her¬≠bi¬≠vores be¬≠cause they pro¬≠vided a lot of fatty, en¬≠ergy-dense meat. These her¬≠bi¬≠vores could be killed with¬≠out us¬≠ing weapons‚Äďjust sim¬≠ply 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 hu¬≠man cul¬≠tures ate dif¬≠fer¬≠ent amounts of meat, and thus there was a wide range of per-capita meat/‚Äčpro¬≠tein in¬≠takes. Meat in tra¬≠di¬≠tional agri¬≠cul¬≠tural so¬≠ci¬≠eties About 10,000 years ago, hu¬≠mans learned how to farm. Farming food in¬≠creased the pop¬≠u¬≠la¬≠tion den¬≠sity but si¬≠mul¬≠ta¬≠ne¬≠ously de¬≠creased the av¬≠er¬≠age qual¬≠ity of nu¬≠tri¬≠tion.

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 Ô¨Ārst re¬≠frig¬≠er¬≠ated ship¬≠ments of meat be¬≠gan in the 1870s, which helped the ex¬≠pan¬≠sion of world¬≠wide 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 cen¬≠tury, the pop¬≠u¬≠la¬≠tion of af¬≠Ô¨āu¬≠ent coun¬≠tries rep¬≠re¬≠sented only one-Ô¨Āfth of the global to¬≠tal but pro¬≠duced and con¬≠sumed two-Ô¨Āfths of all red meat and three-Ô¨Āfths of all poul¬≠try.

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 turn¬≠ing feed grain into meat. They con¬≠sume about 50% more en¬≠ergy than pigs. Chickens are the best con¬≠vert¬≠ers of plant-to-an¬≠i¬≠mal pro¬≠tein‚Äďat about 20% ef¬≠Ô¨Ā¬≠ciency.

Overall, the three ma¬≠jor an¬≠i¬≠mals‚Äďcows, pigs, and chick¬≠ens‚Äďare ex¬≠tremely in¬≠ef¬≠Ô¨Ā¬≠cient at cre¬≠at¬≠ing pro¬≠tein. About 80 to 96% of plant pro¬≠tein con¬≠sumed is not con¬≠verted to an¬≠i¬≠mal pro¬≠tein.

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 cur¬≠rent crop yields and feed¬≠ing prac¬≠tices, the en¬≠tire world can¬≠not eat meat at the same rate as the af¬≠Ô¨āu¬≠ent coun¬≠tries. To achieve meat-eat¬≠ing for all, we would need to make ad¬≠vances in bio¬≠engi¬≠neer¬≠ing.

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 wa¬≠ter to raise an¬≠i¬≠mals and grow feed crops. Thus, meat/‚Äčgrain trade can ben¬≠e¬≠Ô¨Āt coun¬≠tries with scarce wa¬≠ter re¬≠sources. This sit¬≠u¬≠a¬≠tion can po¬≠ten¬≠tially set up a com¬≠par¬≠a¬≠tive ad¬≠van¬≠tage in trade for wa¬≠ter-rich pro¬≠duc¬≠ers.

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 an¬≠i¬≠mals we eat are so¬≠cial an¬≠i¬≠mals‚Äďand this leads to var¬≠i¬≠ous eth¬≠i¬≠cal dilem¬≠mas. Modern farm¬≠ing tech¬≠niques don‚Äôt ex¬≠actly take good care of the an¬≠i¬≠mals.

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 sta¬≠ble be¬≠tween 1960 and 1980‚Äďat about 25% of the pop¬≠u¬≠la¬≠tion. In the 1980s, this per¬≠cent¬≠age 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 di¬≠ets have be¬≠come less dis¬≠ci¬≠plined‚Äďwhich has gone hand-in-hand with obese peo¬≠ple claim¬≠ing to be vic¬≠tims.

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.