{"id":21507,"date":"2026-07-28T15:49:02","date_gmt":"2026-07-28T19:49:02","guid":{"rendered":"https:\/\/nycphantom.com\/journal\/?p=21507"},"modified":"2026-07-28T22:37:56","modified_gmt":"2026-07-29T02:37:56","slug":"the-mystery-of-1-billion-heartbeats-why-every-mammal-seems-to-have-1-billion-heartbeats","status":"publish","type":"post","link":"https:\/\/nycphantom.com\/journal\/?p=21507","title":{"rendered":"The Mystery of 1 Billion Heartbeats - Why Every Mammal Seems to Have 1 Billion Heartbeats"},"content":{"rendered":"\n<p class=\"wp-block-paragraph\"><strong>Nadia's heart rate<\/strong> is faster than mine on average, I may know why now:<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Veritasium did an <a href=\"https:\/\/turboscribe.ai\/transcript\/share\/4800837202901328859\/xqo89nv2_aQ3OvyDpRF8Jf_D7O6eOu_RHRlsW7JXzFI\/why-does-every-mammal-get-1-billion-heartbeats-in-their-life\">interesting study<\/a> on this and this is my summary and reflection.<\/p>\n\n\n\n<figure class=\"wp-block-embed is-type-video is-provider-youtube wp-block-embed-youtube wp-embed-aspect-16-9 wp-has-aspect-ratio\"><div class=\"wp-block-embed__wrapper\">\n<iframe loading=\"lazy\" title=\"Why does every mammal get 1 billion heartbeats in their life?\" width=\"640\" height=\"360\" src=\"https:\/\/www.youtube.com\/embed\/tL9Lw250spc?feature=oembed\" frameborder=\"0\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share\" referrerpolicy=\"strict-origin-when-cross-origin\" allowfullscreen><\/iframe>\n<\/div><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">The <strong>smaller<\/strong> the mammals, the <strong>faster <\/strong>their heart rates and <strong>shorter <\/strong>their lifespans; vice versa for larger mammals, according to statistics.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">For humans however, the exception to this apparent rule began around <strong>1850<\/strong>, when science and modern sanitation improved, and <strong>tripled our life expectancy to 3 billion heartbeats<\/strong>.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Metabolic Rate = Metabolic need = the baseline amount of energy (calories) an organism requires to stay alive and keep its body functioning properly (pumping blood, breathing, cellular upkeep, brain function, temperature regulation) over a given period.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">The guesses in this scaling has been debated between <strong>the Surface Law<\/strong>, 2\/3 scaling, thus Metabolic Rate or need = M<sup>2\/3<\/sup>) and <strong>Kleiber's Law<\/strong> (3\/4 scaling, M<sup>3\/4<\/sup>), and Kleiber's Law seems to hold for now.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Surface law's 2\/3 scaling comes from three-dimensional Volume (Mass, M), i.e. scales with radius cubed (r<sup>3<\/sup>) in relation to a two-dimensional surface, i.e. scales with radius squared (r<sup>2<\/sup>). Surface area is thus proportional to Mass to the 2\/3 power.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Kleiber found that the empirical data seems to align more with a 3\/4 power scaling, in 1932. No one knew why until <strong>WBE Theory<\/strong> finally provided in 1997 the theoretical derivation, proving that the 3\/4 exponent is the mathematical result of resources moving through a <strong>fractal<\/strong>, space-filling network of blood vessels.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">The reason smaller mammals have faster heart rates comes down to a fundamental physical problem: <strong>they lose heat incredibly fast.<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Because of the geometry of size, a small mammal has a <strong>huge amount of skin (surface area) relative to its tiny body mass (volume)<\/strong>.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">No wonder Nadia gets cold so quickly than I do. Because she has a smaller body mass, she has a <strong>higher surface-area-to-volume ratio<\/strong> than you do. Also men's <strong>muscle factor <\/strong>(more muscle mass = more metabolic resting heat) has advantage over women's. This also explain her side of the bed is so hot.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">On the slightly different note: I'm going to have her <strong>cutback coffee<\/strong> (calming the nerves that's amped up by adrenaline triggered by caffeine which does cause <strong>hand tremor<\/strong>) by gradually switching to herbal tea instead of quitting cold turkey. And also hand muscle training on a stress ball.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">On other notes: Uses of Scaling Laws in Cities<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">The concepts of scaling also apply to human cities based on their populations [<a target=\"_blank\" rel=\"noreferrer noopener\" href=\"https:\/\/www.youtube.com\/watch?v=tL9Lw250spc&amp;t=178\">02:58<\/a>]:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Sublinear Scaling (0.85 Exponent):<\/strong> Infrastructure like roads, electrical cables, and gas stations scale efficiently [<a href=\"https:\/\/www.youtube.com\/watch?v=tL9Lw250spc&amp;t=1639\" target=\"_blank\" rel=\"noreferrer noopener\">27:19<\/a>]. Doubling a city's size requires only about 74% more gas stations, making cities remarkably \"green\" due to shared resources [<a href=\"https:\/\/www.youtube.com\/watch?v=tL9Lw250spc&amp;t=1623\" target=\"_blank\" rel=\"noreferrer noopener\">27:03<\/a>, <a href=\"https:\/\/www.youtube.com\/watch?v=tL9Lw250spc&amp;t=1656\" target=\"_blank\" rel=\"noreferrer noopener\">27:36<\/a>].<\/li>\n\n\n\n<li><strong>Superlinear Scaling (1.15 Exponent):<\/strong> Socioeconomic factors scale at an accelerated rate [<a href=\"https:\/\/www.youtube.com\/watch?v=tL9Lw250spc&amp;t=1662\" target=\"_blank\" rel=\"noreferrer noopener\">27:42<\/a>]. Doubling a city's population yields a 120% increase in total wages, wealth, and innovation (patents) [<a href=\"https:\/\/www.youtube.com\/watch?v=tL9Lw250spc&amp;t=1662\" target=\"_blank\" rel=\"noreferrer noopener\">27:42<\/a>]. However, negative traits like crime and disease also increase by that same 120% margin [<a href=\"https:\/\/www.youtube.com\/watch?v=tL9Lw250spc&amp;t=1553\" target=\"_blank\" rel=\"noreferrer noopener\">25:53<\/a>, <a href=\"https:\/\/www.youtube.com\/watch?v=tL9Lw250spc&amp;t=1575\" target=\"_blank\" rel=\"noreferrer noopener\">26:15<\/a>].<\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"<p>Nadia's heart rate is faster than mine on average, I may know why now: Veritasium did an interesting study on this and this is my summary and reflection. The smaller the mammals, the faster their heart rates and shorter their &hellip; <a href=\"https:\/\/nycphantom.com\/journal\/?p=21507\">Continue reading <span class=\"meta-nav\">&rarr;<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[23,13],"tags":[],"class_list":["post-21507","post","type-post","status-publish","format-standard","hentry","category-biology","category-reflection"],"_links":{"self":[{"href":"https:\/\/nycphantom.com\/journal\/index.php?rest_route=\/wp\/v2\/posts\/21507","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/nycphantom.com\/journal\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/nycphantom.com\/journal\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/nycphantom.com\/journal\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/nycphantom.com\/journal\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=21507"}],"version-history":[{"count":5,"href":"https:\/\/nycphantom.com\/journal\/index.php?rest_route=\/wp\/v2\/posts\/21507\/revisions"}],"predecessor-version":[{"id":21516,"href":"https:\/\/nycphantom.com\/journal\/index.php?rest_route=\/wp\/v2\/posts\/21507\/revisions\/21516"}],"wp:attachment":[{"href":"https:\/\/nycphantom.com\/journal\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=21507"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/nycphantom.com\/journal\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=21507"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/nycphantom.com\/journal\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=21507"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}