A civilisation now lost in time, the ancient Aztecs were masters of science and technology, creating medicines, machines and mega-structures unsurpassed on Earth.
and it remained the heart of their empire until the Spanish invasion of Hernán Cortés led to its collapse in 1520.
Unfortunately, much of this knowledge was lost forever when the Spanish conquistadors of Hernán Cortés brought the civilisation to their knees in the early-16th century, with these supposedly heretical texts burned en masse. Luckily, a few records of Aztec scientific knowledge survived and today historians are working tirelessly to unlock their secrets. Read on to discover some of their most impressive scientific knowledge.
Aztec Alphabet
If you needed any other evidence of the advanced state of Aztec learning then analysis of the society’s alphabet seals the deal. The Aztec alphabet was split into three different sections, utilising pictograms, ideograms and phonograms. Pictograms were symbols representing exactly what they were, so a snake pictogram would mean ‘snake’ and be pronounced ‘snake.’ On the other hand, phonograms were pictures representing sounds, a lot like the vast majority of alphabets today, with letters representing specific sounds that words can be constructed from.
The Aztec alphabet contained four basic vowels and a large selection of consonants including cu, hu and ch. Finally, ideograms were the most abstract part of the alphabet, consisting of symbols that represented an entire idea. For example, a footprint symbol in the Aztec alphabet represented a journey or passage of time, so would frequently be used to depict the movements of famous people in stories.
Marvelous mathematicians
Buried deep within the Codex Vergara (a cadastral manuscript) lies a wealth of information about Aztec mathematics, which has now been decoded and revealed to be a vigesimal system rather than our decimal system in use today. The Aztec vigesimal system uses 20 as its base, with written dots equating to one, hyphen-style bars equating to five and various other symbols accounting for 20 and multiples thereof. According to the Vergara, as well as other codices, this system was employed for tax purposes, which was largely based on land owned, as well as for commerce, with quantities of produce traded with precision thanks to the creation of hard rules for addition, subtraction, division and multiplication. Of all the pre- Columbian peoples of Central America, the Aztecs
were the most accomplished mathematicians, using a unique numbering system for arithmetic, record keeping and even in a taxation system for Tenochtitlan and the surviving lands.
Land was also measured mathematically, with a selection of algorithms utilised to calculate area, the most basic being the multiplication of length by width, while multiplying the averages of two opposite sides by an adjacent side used for irregular shapes. Land was measured in terms of ‘land rods’, which was the standard Aztec unit of linear measurement, measuring in at 2.5 metres (8 feet) in length. For measurements under a land rod, a variety of other symbols including arrows, hearts and hands were used for indication. This level of mathematical precision also stretched into other areas, such as construction, which was one area where the Aztecs were most advanced in terms of technological prowess.
Kings of construction
As can be seen in the ‘El Templo Mayor’ boxout, the Aztecs became specialists at building stepped pyramid temples and public buildings, cutting, carving and hauling vast stone blocks and arranging them with exact geometrical precision. They were also excellent house builders, with even the poorest commoner typically living under human-made shelters, with the average dwelling measuring in at approximately 20 square metres (215 square foot) in the capital city of Tenochtitlan.
Due to their environment, Aztec houses tended to be built on elevated platforms crafted from wattle-and-daub, with codices indicating that they stood approximately 40 centimetres (15 inches) off the surface. This was particularly important in the swampy city of Tenochtitlan. Walls were constructed from wooden frames and then filled in with stone, sand, lime and clay with adobe bricks – sculpted from a mixture of water, sand and clay – very common.
Roofs ranged in both design and construction materials, with both flat-pole and peaked roofs widespread and everything from straw through to wood and bricks used. Judging from excavated evidence as well as the information deciphered from surviving codices, a selection of construction tools were utilised in each build, ranging from cutting tools such as knifes and axes through to trowels and picks, with additional carvings undertaken if the house’s patron was particularly wealthy. Important nobles would often have their dwellings painted, with the Aztecs using natural plant and animal ingredients – such as beetles, eg the cochineal species containing red carminic acid – to create coloured dyes and paints. Buildings were arranged within a city in terms of importance, which relied largely upon the Aztecs’ mastery of astronomy.
Awesome astronomers
As revealed in the Aztec Codex Mendoza, Aztec priests and nobles were accomplished astronomers, accruing and storing the knowledge of deciphering the night sky for centuries and handing it down through generations in isolation from the wider world. Records show that as well as being capable of accurately tracking the movements of celestial bodies such as the Sun, Moon and other planets – which they accomplished by placing sets of crossed wooden poles along their site lines – they utilised that information to create a religious and solar calendar as well as orientate their key structures along equinoctial lines. For example, the Templo Mayor of Tenochtitlan was aligned so that on the spring equinox (21 March) the Sun rose directly between its two top-mounted shrines, with ceremonies held there in dedication of it.
From their ability to navigate by the position of the stars, through to their creation of solar calendar and onto their construction of temples in perfect alignment so that the Sun’s rays shone focussed on their summit during the equinox, the Aztecs were truly expert astronomers. Astronomy was practised primarily by Aztec nobility and priests, with the latter using dedicated observatories within temples to track the movements of celestial bodies. By harnessing the knowledge of the celestial cycles, the Aztecs could also use astronomy to track the length of a solar year and lunar month, as well as determine the duration of Venus’s orbit and the prediction of any solar or lunar eclipses.
The Aztec Calendar
Understand this unique time-keeping system now.
The Aztec calendar consisted of a 365-day cycle, referred to as a ‘year count’, and a 260-day cycle, referred to as a ‘day count’. Together, these two cycles formed a 52-year century or ‘calendar round’ for the civilisation, with the former based on the movements of the sun and the latter based on religious belief. The year-count cycle consisted of eighteen 20-day months, with a separate five-day period at the end that was considered unlucky. The day-count cycle consisted of twenty 13-day periods referred to as trecena, with each trecena attributed to a different god.
While it is obvious that many parts of the their calendar system were inaccurate, the fact that the Aztecs could harness their advancements in astronomy and mathematics to create a calendar that was so close to an Earth year while deep in the isolated jungles of central America, is a remarkable feat. Furthermore, despite the Aztecs’ religious calendar being centred on mythological deities, many of its aspects are based on scientific study of the Earth’s environment and atmosphere.
A good representation of the Aztec religious calendar – the cycle referred to as the day count – can be seen in the Aztec calendar stone, a massive 3.7m (12ft) in diameter, 24-ton ornate sun stone that once held great importance in the ancient civilisation of the Aztecs. The stone, which demonstrates the Aztecs’ advanced understanding of geometry, is broken down into constituent parts in the diagram to the right.
Formidable farmers
One area where the Aztecs utilised their scientific and technological ingenuity to maximum effect was in their farming practices. Living in and around large swamps and lake-heavy areas of Central America, the Aztecs designed and employed terracing and artificial island systems to ensure crops had optimal land area to grow.
They built aqueducts and dug channels to ensure crops were irrigated, and crafted their own tools and basic farming machines for crop planting and harvesting. The most common crop grown by the Aztecs was maize (corn), but due to their mastery of the art many other crops such as squashes, beans, avocados and guavas were delivered. With their largest city-state of Tenochtitlan built in the middle of Lake Texcoco and housing north of 200,000 people, a large and consistent food supply was necessary for the Aztecs.
Their mastery of irrigation and the chinampas construction system meant that vast fields of produce were grown all-year-round, with maize, beans, squash and much more grown with a frequency unsurpassed on the continent. The Aztecs also harnessed knowledge of nutrition, specifically in terms of the health of soils and water when used to grow crops.
Indeed, the Aztecs operated one of the most advanced crop-rotation systems ever created: their knowledge that certain crops deplete the land of specific nutrients was used to ensure soils were always cycled for a new type of produce, granting it time to recover. Further, specific crops were partnered with ones ensuring a nutritional balance within the planting area, with the combination ensuring that farms maximised crop yield for every square metre of land used. The Aztecs also grew many herbs within their systems, with these used in another specialist Aztec science; herbology.
Tenochtitlan
How did the Aztecs create a city in the middle of a swamp?
What makes Tenochtitlan truly remarkable is that the entire city was built in the middle of a lake. This massive Aztec metropolis floated on Lake Texcoco, one of the largest inland water masses in Mexico. This was possible thanks to the Aztecs inventing and then mastering the construction of chinampas, raised artificial islands that could be used both for construction and agricultural purposes. These artificial islands were created by first staking out the lake bed with wooden poles and fencing off the rest of the lake with wattle. The fenced-off area was then layered with mud, sediments and decaying organic matter repeatedly until it rose above the water level of the lake. Finally, willow or cypress trees would be planted in each corner, which when grown acted as stabilisers for the landmass, with their roots binding them.
These chinampas were built in straight lines and separated with small canals, thereby creating a thoroughfare for travel around them in canoes. Once an adequate surface area had been built through the chinampas system, buildings could then be constructed on top or crops planted en masse, with the fertile soil base and superb water source meaning that any plant grew rapidly and with a high crop yield. These artificial, reef-style islands were then interconnected with a series of causeways and terracotta aqueducts, the latter supplying the inhabitants of the floating city with fresh water from the nearby Chapultepec springs.
Great Tenochtitlan
Towards 1325, the Aztec settled in the region of the Texcoco lake, south of Mexico valley. They built the city of Tenochtitlan on a long islet that reached a population of more than 200,000 inhabitants, the double of any European city of the time. The city was enlarged towards the nearby islands. It was divided into four neighbourhoods where the twenty clans or calpulli, that grouped the Aztec families, were distributed. Each calpulli was relatively autonomous; it had its own temples, schools and markets. Tens of canals crossed the city sailed by 50,000 reed boats every day and crossed by wooden bridges that were removed at night.
Masters of medicine
Aztecs’ understanding of medicinal science was incredibly advanced for the time. In a period where most western nations were still addressing illnesses with either prayer or misguided placebos, Aztec civilisation granted prestige to the position of doctor and encouraged them to study the human body and potential remedies in depth.
Among these studies, those of plants and their medicinal effects were central, from which Aztec doctors fashioned antispasmodic medications capable of preventing muscle spasms during surgery, according to codices such as the Codex Barberini, commonly referred to as the ‘Aztec Herbal.’ This was primarily achieved through the use of the passion flower. Other inventions included organic paste painkillers, liquid rubber for curing earaches and ground obsidian for the sealing of wounds.
Aztec physicians became the most skilled herbalists in the world, thanks to their in-depth study of the human body and their environment. Indeed, along with the establishment of hospitals, Aztec doctors were encouraged to undertake research, studying the effects of plants grown in large communal gardens. On top of this scientific approach, Aztec doctors accrued significant general medical knowledge that today we take for granted, including that people should not look at eclipses to prevent against vision damage, steam baths could cleanse the skin and sinuses and that specific foods were better for the human body than others.
These vast banks of knowledge allowed the Aztecs to scientifically and technologically surpass many of Earth’s other ancient cultures, and in a fraction of the time, with the Mesoamerican peoples taking mere centuries to build a society the others – such as Ancient Egypts – took thousands of years to build. The secrets of science that they uncovered have, on the whole, withstood the test of time, with salvaged knowledge from the ancient culture leading to further developments in their field and contributing greatly to the sciences as they exist today.
El Templo Mayor
How did the Aztecs build this most awesome of citadels?
Originally constructed in 1325 and then added to and extended six times afterwards, the massive Templo Mayor citadel of Tenochtitlan was surely one of the wonders of the ancient world, towering over the Aztec city state’s other structures at close to 30 m (90 ft) in height. Indeed, by the time it was eventually sacked and destroyed by the Spanish conquistadors of the 16th century, the pyramid temple consisted of four steep sloped terraces topped with a great platform measuring 80 x 100 m (262 x 328 ft), with a further two sets of stone stairs leading to a pair of grand shrines. Every part of the temple was decorated with carvings and surrounding it lay a vast stone-slabbed precinct that measured 4,000 m2 (43,000 ft2) filled with balustrades and further decorative aspects. Not bad considering it was constructed by slaves and working-class craftsmen under the direction of a ruling class of learned architects and mathematicians.
The advanced construction techniques mastered by the Aztecs over their civilisation’s tenure in Central America. From the sculpting of vast blocks of stone from dedicated quarries for its terraces – the Aztecs were the first culture to industrialise this process in Central and South America – to utilising scaffolds and rope lifts to transport men and tools up its structure and onto the expert craftsmanship that allowed them to carve vast ornamental dragons and mix polychrome paints to decorate the temple’s exterior, El Templo Mayor became the temple of temples. Indeed, if it were not for the sudden obliteration of their society by the Spanish conquistador Hernán Cortés, who knows how much higher and more complicated their temples could have grown ?