Human enhancement is the natural, artificial, or technological alteration of the human body in order to enhance physical or mental capabilities. Technologies Existing technologies Three forms of human enhancement currently exist: reproductive, physical, and mental. Reproductive enhancements include embryo selection by preimplantation genetic diagnosis, cytoplasmictransfer, and in vitro-generated gametes. Physical enhancements include cosmetics (plastic surgery & orthodontics), Drug-induced (doping & performance-enhancing drugs), functional (prosthetics & powered exoskeletons), Medical (implants (e.g. pacemaker) & organ replacements (e.g. bionic lenses)), and strength training (weights (e.g. barbells) & dietary supplement)). Examples of mental enhancements are nootropics, neurostimulation, and supplements that improve mental functions. Computers, mobile phones, and Internet can also be used to enhance cognitive efficiency. Notable efforts in human augmentation are driven by the interconnected Internet of Things (IoT) devices, including wearable electronics (e.g., augmented reality glasses, smart watches, smart textile), personal drones, on-body and in-body nanonetworks. Emerging technologies Many different forms of human enhancing technologies are either on the way or are currently being tested and trialed. A few of these emerging technologies include: human genetic engineering (gene therapy), neurotechnology (neural implants and brain–computer interfaces), cyberware, strategies for engineered negligible senescence, nanomedicine, and 3D bioprinting. Variants of human genetic engineering with so far limited usage include the artificial creation of human-animal hybrids (where each cell has partly human and partly animal genetic contents) and human-animal chimeras (where some cells are human and some cells are animal in origin). Speculative technologies A few hypothetical human enhancement technologies are under speculation, such as: mind uploading, exocortex, and endogenous artificial nutrition. Mind uploading is the hypothetical process of "transferring"/"uploading" or copying a conscious mind from a brain to a non-biological substrate by scanning and mapping a biological brain in detail and copying its state into a computer system or another computational device. Exocortex can be defined as a theoretical artificial external information processing system that would augment a brain's biological high-level cognitive processes. Endogenous artificial nutrition can be similar to having a radioisotope generator that resynthesizes glucose (similarly to photosynthesis), amino acids and vitamins from their degradation products, theoretically availing for weeks without food if necessary. Nootropics There are many substances that are purported to have promise in augmenting human cognition by various means. These substances are called nootropics and can potentially benefit individuals with cognitive decline and many different disorders, but may also be capable of yielding results in cognitively healthy persons. Generally speaking,