Editing 1338: Land Mammals

{{comic
| number    = 1338
| date      = March 5, 2014
| title     = Land Mammals
| image     = land_mammals.png
| titletext = Bacteria still outweigh us thousands to one--and that's not even counting the several pounds of them in your body.
}}

==Explanation==
This comic shows the total weight of {{w|Human|mankind}} and all other land {{w|mammals}}. Only a few centuries ago, {{w|humans}}, their {{w|pets}} and {{w|livestock}} came to make up a great proportion of the earth's land mammal {{w|biomass}}. Note that only land-dwelling mammals are taken into account, so for instance {{w|whales}} and {{w|sea cows}} will not be included. (Whether this only covers animals that cannot live on land or any {{w|marine mammals}} like for instance {{w|Pinniped|seals}} and {{w|walrus}}, is not clear).

The design of the blocks loosely resembles a {{w|Cell (biology)|cell}}. This could be a reference to how these animals support humans, analogous to a cell supporting a central nucleus. If so, it seems that all the animals in this diagram, {{w|wild animals|wild}} or {{w|Domestication|domestic}}, in some way support human activity.

The title text states that {{w|bacteria}} outweigh us thousands to one, without counting the several pounds of {{w|Human microbiota|bacteria in our body}} that are considered part of our own weight (like {{w|Gut flora}}). The aforementioned cell could also be a bacterium, making it a possible reference to the title text, since 1256 blocks have been used to sketch the "cell", and bacteria outweigh us by about this factor.

This comic may be a [[Nerd Sniping|nerd snipe]] from [[Randall]], challenging his readers to figure out the missing parts.

Randall also discusses animal biomass in [http://whatif.xkcd.com/123/ Fairy Demographics] in which he compares the biomass of "fairies" to humans, horses, and humpback whales.

===Weight===
According to the diagram, there are 358 million tons of humans, 864 million tons of pets and livestock, of which 520 million tons comes from {{w|cattle}}, and 34 million tons of wild animals; for a total of 1.256 billion tons.
The number of blocks represents the weight of the group in millions of tons = billions of kg. Note that some entries have the same number of blocks, and thus have the same rank.

====Humans====
Cattle, in aggregate, are much heavier than the human population. Humans outweigh both {{w|sheep}} and {{w|Domestic pig|pigs}} put together. This may be a surprise for people in the countries that produce the majority of meat from such animals, because here these animals outweigh the population. But there are many parts of the world where especially pigs are not eaten, and it is not every where that sheep is in great demand. And especially in the some of the most populations dense regions in the {{w|Third World}} meat is not something you can afford to eat on a regular basis.

====Our pets and livestock====
There are 13 distinct blocks of pets and live stock; only the top 5 are labeled - in order of weight they are: Cattle, Sheep, Pigs, {{w|Goats}} and {{w|Horses}}. Cattle, in aggregate, are much heavier than the human population, which has been inserted in the table for comparison:
{| class="wikitable sortable" style="width: auto; text-align: center; font-size: 95%; table-layout: fixed; line-height:1.25"
|-
! Total&nbsp;Rank
! Weight&nbsp; (Millions of tons)
! Name
|-
| {{sort|00001|1}}
| {{sort|00520|520}}
|  Cattle
|-
| {{sort|00001|2}}
| {{sort|00358|358}}
|  (Humans)
|-
| {{sort|00003|3}}
| {{sort|00135|135}}
| Sheep
|-
| {{sort|00004|4}}
| {{sort|00090|90}}
| Pigs
|-
| {{sort|00005|5}}
| {{sort|00039|39}}
| Goats
|-
| {{sort|00006|6}}
| {{sort|00029|29}}
| Horses
|-
| {{sort|00007|7}}
| {{sort|00013|13}}
| Unlabeled
|-
| {{sort|00009|9}}
| {{sort|00008|8}}
| Unlabeled
|-
| {{sort|00010|10}}
| {{sort|00007|7}}
| Unlabeled
|-
| {{sort|00010|10}}
| {{sort|00007|7}}
| Unlabeled
|-
| {{sort|00013|13}}
| {{sort|00006|6}}
| Unlabeled
|-
| {{sort|00014|14}}
| {{sort|00005|5}}
| Unlabeled
|-
| {{sort|00017|17}}
| {{sort|00003|3}}
| Unlabeled
|-
| {{sort|00019|19}}
| {{sort|00002|2}}
| Unlabeled
|-
|}

====Wild Animals====
There are 8 distinct blocks of wild animal ({{w|elephants}} and 7 others). The elephant is the only type of wild animal to be singled out in the comic. This may possibly be due to elephants being the largest land mammal. And yes, the world's heaviest land animal only takes up one square. Also interesting is that the largest group of wild animals only comes in on a tied 8 place in the ranking (which is shared between the two tables).
{| class="wikitable sortable" style="width: auto; text-align: center; font-size: 95%; table-layout: fixed; line-height:1.25"
|-
! Rank
! Weight&nbsp; (Millions of tons)
! Name
|-
| {{sort|00008|8}}
| {{sort|00010|10}}
| Unlabeled
|-
| {{sort|00010|10}}
| {{sort|00007|7}}
| Unlabeled
|-
| {{sort|00014|14}}
| {{sort|00005|5}}
| Unlabeled
|-
| {{sort|00016|16}}
| {{sort|00004|4}}
| Unlabeled
|-
| {{sort|00017|17}}
| {{sort|00003|3}}
| Unlabeled
|-
| {{sort|00019|19}}
| {{sort|00002|2}}
| Unlabeled
|-
| {{sort|00019|19}}
| {{sort|00002|2}}
| Unlabeled
|-
| {{sort|00022|22}}
| {{sort|00001|1}}
| Elephants
|-
|}

====References====
The comic references the book ''[https://www.amazon.com/exec/obidos/ASIN/0262692988/vaclavsmil-20/ The Earth's Biosphere: Evolution, Dynamics, and Change]'' by {{W|Vaclav Smil}} as the source for most of the data. A few other sources have also been used, but were not referenced.
On page 186 of Smil's book, there is a bar chart with the following values:
{| class="wikitable sortable" style="width: auto; text-align: center; font-size: 95%; table-layout: fixed; line-height:1.25"
|-
! (Millions of tons)
! Name
|-
| {{sort|00008|0.8}}
| Elephants
|-
| {{sort|00400|40}}
| Horses
|-
| {{sort|01000|100}}
| Pigs
|-
| {{sort|04500|450}}
| Cattle
|-
| {{sort|02800|280}}
|  People
|-
| {{sort|00800|80}}
|  Whales
|-
| {{sort|00300|30}}
| all&nbsp;wild&nbsp;{{w|vertebrates}}
|-
| {{sort|06500|650}}
| all&nbsp;domesticated&nbsp;vertebrates
|-
|}
Note that all labelled non-human animals are in this table. It seems that this table was the source of most of the data in the comic.  Only land dwelling mammals are taken into account. Whales, wild vertebrates, and domesticated vertebrates are not included in the comic.

====Unlabeled Animals====
These are guesses about the identity of the unlabeled animals
{| class="wikitable" style="width: auto; text-align: center; font-size: 95%; table-layout: fixed; line-height:1.25"
|-
! Rank
! Comic weight (Millions of tons)
! Type
! Guess
! Actual Population (Millions)
! Average Weight (kg)
! Total weight (Millions of kg)
! Explanation
|-
| rowspan="1" |7
| rowspan="1" |13
| rowspan="1" |Pets/Livestock
| 
|
|
|
|
|-
| rowspan="1" |8
| rowspan="1" |10
| rowspan="1" |Wild animals
| 
|
|
|
| 
|-
| rowspan="1" |9
| rowspan="1" |8
| rowspan="1" |Pets/Livestock
| 
|
|
|
|
|-
| rowspan="2" |10
| rowspan="2" |7
| rowspan="2" |Pets/Livestock
| {{w|Camel}}
| 17
| 412
| 7004
| Wikipedia lists the number of camels as 17 million. An average weight, based on Wikipedia's numbers for male and female, is about 500&nbsp;kg. So, including the non-adult camels, an average around 400&nbsp;kg seems to be a realistic estimate.
|-
| &nbsp;
| 
| 
| 
| 
|-
| rowspan="1" |10
| rowspan="1" |7
| rowspan="1" |Pets/Livestock
| 
|
| 
|
|
|-
| rowspan="1" |10
| rowspan="1" |7
| rowspan="1" |Wild animals
| 
| 
|
|
|
|-
| rowspan="2" |13
| rowspan="2" |6
| rowspan="2" |Pets/Livestock
| {{w|Dogs}}
| 400
| 15
| 6000
|According to Wikipedia, there are 400 million dogs worldwide. If the average weight is 15&nbsp;kg, there would be 6 blocks.<!-- Small dog=2 kg large dog = 100 kg the log average is about 15 kg. -->
|-
| &nbsp;
| 
| 
|
| 
|-
| rowspan="2" |14
| rowspan="2" |5
| rowspan="2" |Pets/Livestock
| {{w|Donkeys}}
| 41
| 122
| 5002
| There are roughly 41 million {{w|Donkey#Present status|donkeys on Earth}}, with an average weight of about 125&nbsp;kg.
|-
| &nbsp;
| 
| 
|
| 
|-
| rowspan="1" |14
| rowspan="1" |5
| rowspan="1" |Wild animals
| 
|
|
|
|
|-
| rowspan="1" |16
| rowspan="1" |4
| rowspan="1" |Wild animals
| 
|
|
|
|
|-
| rowspan="1" |17
| rowspan="1" |3
| rowspan="1" |Pets/Livestock
| 
|
|
|
|
|-
| rowspan="1" |17
| rowspan="1" |3
| rowspan="1" |Wild animals
| 
|
|
|
|
|-
| rowspan="2" |19
| rowspan="2" |2
| rowspan="2" |Pets/Livestock
| {{w|Cats}}
| 500
| 4
| 2000
| There are 500 million domestic cats worldwide. The average weight of an adult cats is 4.5&nbsp;kg. Factoring in the lighter weight of immature cats, 4&nbsp;kg as an average for all cats, (adult and immature) is within the range of possibility. (According to [[526: Converting to Metric]] cats do weigh 4 kg, only with caption do they reach 4.1 kg).
|-
| &nbsp;
| 
| 
| 
|
|-
| rowspan="1" |19
| rowspan="1" |2
| rowspan="1" |Wild animals
| 
|
|
|
|
|-
| rowspan="2" |19
| rowspan="2" |2
| rowspan="2" |Wild animals
| {{W|Rat#Species and description|Rat}}
| 4000
| 0.5
| 2000
|The {{W|World Health Organization}} estimates 4 billion rats{{Actual citation needed}} worldwide. The average weight of an adult rat is under 500 g. 
|-
| &nbsp;
| 
| 
|
|
|-
|}

==Transcript==
:[Caption at the top of this chart:]
:<big>'''Earth's <big><big>Land Mammals</big></big> by Weight'''</big>

:[Below the caption is a light gray block with a label (in light gray as well) to indicating the value of each block:] 
:<font color="gray">= 1,000,000 tons</font>

:[Below this there is a row with three blocks each in a different color, dark and light gray and green, each block is labeled to the right:] 
:'''Humans'''
:'''Our pets and livestock'''
:'''Wild animals'''

:[The rest of the comic consist of a chart with different groups made up of these individually and differently colored blocks, each grouping representing the weight of a different mammals, except the center part, the only one with dark gray block, which represent humans. The largest group to the left is the only one larger than the humans group in the center. There are 22 groups in total, 1 human group with 358 dark gray block, 13 groups of light gray with a total of 864 blocks and 8 green groups with a total of 34 blocks for a total of 256 blocks. Both the light gray and the green groups are spread out on all sides of the human center group. Only difference is that all the green are on the very outside, whereas some of the smaller light gray groups are close to the core, far from the outside. The five largest groups of light gray blocks are labeled, as well as the smallest group consisting only of a single green block. All the labels has a line pointing to the relevant group and all of them are on the outside of the entire block. Going clockwise from the top left the labels are:]
:<big><font color="gray">Cattle</font></big>
:<big><font color="gray">Pigs</font></big>
:<big><font color="gray">Goats</font></big>
:<big><font color="gray">Sheep</font></big>
:<big><font color="gray">Horses</font></big>
:<big><font color="gray">Elephants</font></big>

:[At the bottom right of the comic is the following gray text with a reference:]
:<font color="gray">Data from Vaclav Smil's ''The Earth's Biosphere: Evolution, Dynamics, and Change'', plus a few other sources.</font>

{{comic discussion}}

[[Category:Charts]]
[[Category:Animals]]